CARE AND OPERATION 

OF Ifc 

CENTRAL OFFICE POWER PLANT 

T K 

(cZ\ I 

ENGINEERING BULLETIN 140 


NEW YORK TELEPHONE COMPANY 










COPYRIGHT DEPOSIT. 


















CARE AND OPERATION 

« 

OF 

CENTRAL OFFICE POWER PLANT 


ENGINEERING BULLETIN 140 








NEW YORK TELEPHONE COMPANY 












TABLE OF CONTENTS 


SECTION Page 

1. MOTORS, GENERATORS AND ASSOCIATED 

APPARATUS 

Definitions . 1 

Operation: Motors D. C. 7 

“ “ A. C. 8 

“ Generators—Charging . 11 

“ “ In Parallel . 12 

“ “ Message Register. 12 

“ “ Coin Collector . 12 

“ “ Ringing . 13 

Reserve Sets . 13 

Power Apparatus in the Hands of Western 

Electric Company . 14 

Troubles: Motors . 15 

11 Generators . 15 

Care and Maintenance: Machines. 18 

“ “ Circuit Breakers, Start¬ 
ing Boxes, Rheostats, Etc. 24 

Reference Figures . 26-43 

2. MERCURY ARC RECTIFIER SETS 

Definitions . 44 

Description . 45 

Operation . 46 

Troubles . 48 

Care and Maintenance . 50 

Reference Figure . 51 

3. GAS ENGINES 

Definitions . 52 

Description . 54 

Operation . 55 

Troubles . 57 

Care and Maintenance. 58 

Reference Figures . 60-64 































SECTION Page 

4. EMERGENCY CHARGING SETS 

Definitions . 65 

Operation . 67 

Troubles . 70 

Care and Maintenance. 71 

Reference Figure . 74 


5. STORAGE BATTERIES 


Definitions . 75 

Description . 78 

Operation . 82 

Care and Maintenance. 85 

Two-Plate Cells . 88 

Troubles . 89 

Reference Figure . 92 


6. PRIMARY BATTERIES 


Definitions . 93 

Chemical Action . 93 

Description: Standard Battery . 94 

“ Caustic Soda Battery. 95 

“ Dry Battery . 97 

Uses . 98 

Tests . 99 


7. POLE CHANGERS 


Definitions . 103 

Description . 105 

Operation . 105 

Reserve Sets . 106 

Troubles . 106 

Care and Maintenance. 107 

Reference Figures .112-114 




























SECTION Page 

8. MISCELLANEOUS POWER AND LIGHTING 

APPARATUS 

Fuses: Definitions . 115 

11 Care and Maintenance. 116 

Switches . 119 

Ammeters and Voltmeters. 119 

Resistance Lamps . 119 

Alarms, Fuse . 120 

Alarms, Machine . 121 

Electric Fans . 123 

Electric Light and Power Circuits: Operation... 123 

“ " “ “ Routine In¬ 
spections 126 

Reference Figures .128-132 

9. VENTILATING PLANTS 

Definitions . 133 

Description . 134 

Operation . 135 

Care and Maintenance. 136 

10. ROUTINE TESTS, INSPECTIONS AND REPORTS 

Motors, Generators and Associated Apparatus... 137 

Mercury Arc Rectifier Sets. 138 

Emergency Charging Sets. 138 

Storage Batteries . 138 

Primary Batteries . 139 

Pole Changers . 139 

Miscellaneous Power and Lighting Apparatus_ 139 

Ventilating Plants . 140 






















LIST OF ILLUSTRATIONS 

;ECTION Page 

1. MOTORS, GENERATORS AND ASSOCIATED 
APPARATUS 

Staggering of Brushes. 26 

Circuit Breaker with Polarized Relay. Overload 

and Reversed Current Protection. 27 

Circuit Breaker, Reversite Type. Overload and 

Reversed Current Protection. 28 

Circuit Breaker, Plain Underload Type. No Pro- , 

tection against Overload. 29 

Coin Collector Generator. 30 

Message Register Generator. 31 

Ringing Generator. (Alternating and Pulsating 

Ringing Currents) . 32 

Ringing Generator. (Superimposed Ringing)... 33 

Differentially Wound Motor. 34 

Shunt Wound Motor. 35 

Rheostat . 36 

Compound Rheostat . 37 

Combined Starting Box and Field Rheostat. 38 

Connections of Oil Immersed Auto Starter or 

Compensator. (2 or 3 phase motor). 39 

Single Phase Motor with Split Phase Starting 

Box . 40 

Single Phase Motor with Split Phase Starting 

Box. (For motors of less than 1 horse power) 41 

Seating Carbon Brushes. 42 

Charging Circuit. 43 

2. MERCURY ARC RECTIFIER SETS 

Mercury Arc Rectifier. 51 

3. GAS ENGINES 

Equalizer . 60 

Side View of Gas Engine. 61 

Lap Joint of Belt. 62 

Section View of Gas Engine. 63 

Muffler . 64 

























4. EMERGENCY CHARGING SETS 

Portable Gasolene Engine Driven Charging Gene¬ 
rator . 74 

5. STORAGE BATTERIES 

Thermometer with Hydrometer Correction Scale 92 

6 . PRIMARY BATTERIES 

7. POLE CHANGERS 

#84 Type Interrupter. 112 

Pole Changer—Pulsating Ringing . 113 

Pole Changer—Superimposed Ringing . 114 

8 . MISCELLANEOUS POWER AND LIGHTING 

APPARATUS 

Fuse Alarm Signal—#24 Type Fuses. 128 

Fuse Alarm Signal for Central Office Fire Drill 

Bell—#24 Type Fuses. 129 

Fuse Alarm Signal—#35 Type Fuses. 130 

Message Register, High and Low Voltage Alarm 131 
Ringing Generator. Low Voltage Alarm. 132 

9. VENTILATING PLANTS 

10. ROUTINE TESTS, INSPECTIONS AND REPORTS 































MOTORS, GENERATORS AND 
ASSOCIATED APPARATUS 


DEFINITIONS 

Armature 

Generally the revolving part of a generator or motor. 

Brushes 

Used on generators or motors; are made of metal, carbon, 
graphite or a combination of these substances and are so 
placed that they bear upon the commutator, collector rings 
or interrupter rings, and conduct the current to or from the 
external circuit. 

Brush Holders 

Devices for supporting the brushes of a generator, motor, 
or interrupter ring. 

Brush Holder Stud 

The detail of the rocker arm on which the brush holders 
are mounted. 

Brush Rocker or Rocker Arm 

The arm or ring on which the brush holders are mounted 
for the purpose of shifting the brushes on the commutator or 
collector ring of a generator or motor. 

Brushes, Staggered 

Brushes so placed that those on one stud will overlap the 
part of the commutator covered by those on the adjacent 
stud to insure even commutator wear. (See page 26) 

Choke Coil 

v , r ... * . ,~1 I II {•! *.*. 

A coil of very low ohmic resistance and high impedance 
placed in the charging circuit and between storage battery 
and battery driven machines for the purpose of smoothing 
out fluctuations in current caused by commutation. 

1 






Circuit Breaker 

A device for opening a circuit automatically when the 
current increases above, or decreases below, the specified 
limits. (See pages 27, 28 and 29) 

Collector Rings 

Solid brass or copper rings attached to and revolving with 
the armature of a ringing generator, and connected to the 
alternating current winding, and which serve to conduct the 
current through the brushes to the external circuit. 

Collector Rings, Split 

A collector ring divided into two approximately equal seg¬ 
ments, connected to and revolving with the armature of a 
ringing generator, which serve to conduct the positive and 
negative impulses through the brushes to the external circuit. 

Commutator 

Insulated copper segments, assembled in cylindrical form, 
at the end of and connected to the armature windings, and 
which serve to conduct the current through the brushes to 
or from the external circuit. 

Commutator Bar or Segment 
One of the insulated copper sections of the commutator. 

Commutator Tang 

The end of the commutator bar to which the armature 
winding is connected. 

Direct Connected Set —See Motor Generator Set 

Dynamotor 

A machine having a motor and generator winding on the 
same armature, with a common field. This term is also ap¬ 
plied to certain ringing generators having a separate arma¬ 
ture winding to excite the field. 


2 


Field Windings 


The copper wire coils which are wound on the stationary 
pole pieces of motors and generators. 

Generator 

Any mechanically driven machine for producing electric 
current. 

Generator, Charging 

A direct current generator used to charge storage batteries. 
Generator, Coin Collector 

A direct current generator used to furnish current for 
operating coin collector apparatus. (See page 30) 

Generator, Message Register 

A direct current generator used to furnish current for 
operating message registers. (See page 31) 

Generator, Ringing 

A generator used to furnish alternating and pulsating 
ringing currents. (See pages 32 and 33) 

Generator, Shunt Wound 

A generator having the field winding connected in parallel 
with the armature winding and the external circuit. (See 
pages 27, 28 and 29) 

Generator, Compound Wound 

A generator having two distinct field windings, one of 
which is connected in parallel and the other in series with 
the armature winding and the external circuit. (See pages 
30 and 31) 


3 












Interrupters 

A commutating apparatus connected to a ringing generator 
for the purpose of interrupting a direct, pulsating, super¬ 
imposed or alternating current, in order to produce a tone 
or operate a signal. 

For #84 Type, See Section on Pole Changers. 

Motor 

A rotating machine which transforms electrical energy 
into mechanical power. 

Motor, Alternating Current 

A motor operated by alternating current. Those generally 
used are of the induction type and may be single phase, 
two phase, or three phase. 

Motor, Direct Current 

A motor operated by direct current. 

Motor, Differentially Wound 

A direct current motor having two distinct field windings, 
one of which is connected in parallel and the other in series 
with the armature winding and the external circuit. These 
windings are so connected that they are magnetically opposed, 
for the purpose of speed regulation. (See page 34) 

Motor, Shunt Wound 

A direct current motor having the field winding connected 
in parallel with the armature winding and the external 
circuit. (See page 35) 

Motor-Generator Set 

A combination of a motor and a generator mounted on a 
common base, with the shafts coupled together. 


4 


Oil Gauge 


A glass tube for indicating the height of the oil in the 
reservoir. 

Oil Rings 

Metal rings placed loosely upon the shafts of motors and 
generators and which, in revolving, carry oil from the res¬ 
ervoir to the bearings. 

Pole Pieces 

Generally, stationary parts of a generator or motor between 
which the armature revolves, and which are magnetized by 
the current passing through the field windings. 

Reserve Set 

A charging, ringing, message register or coin collector 
unit which is intended to be used in case of failure of the 
regular set. 

Residual Magnetism 

The magnetism retained by the poles of a generator after 
the exciting current flowing in the field windings has been 
interrupted. 


Rheostat 

A variable resistance, adjusted by a hand wheel or lever, 
connected in series with the apparatus through which it is 
desired to regulate the current flow. (See page 36) 

Rheostat, Charging 

A rheostat placed in series with a source of direct current 
supply to control the flow of current through a battery. 







Rheostat, Compound 

A main and auxiliary field rheostat connected in series. 
The approximate adjustment is obtained with the main rheo¬ 
stat and then the exact adjustment by using the auxiliary 
rheostat. (See page 37) 

Rheostat, Field 

A rheostat connected in series with the field windings of 
a generator or motor for varying the current flow through 
the field windings thereby regulating the voltage or speed. 

Rheostat, Starting —See Starting Box 

Split Rings—See Collector Rings 

Starting Box, Direct Current 

A rheostat equipped with an overload and no voltage re¬ 
leasing device, wired in series with the armature circuit of a 
direct current motor for starting it gradually. (See page 35) 

Starting Box Combined with Field Rheostat 

A device used in connection with battery driven ringing 
motor-generator sets which combines the function of a start¬ 
ing box and field rheostat as described above. The field 
rheostat feature is used to obtain a constant speed under 
varied battery voltages. (See page 38) 

Starting Box, Single Phase Motors 

A device so arranged that with resistance and impedance 
the phase can be split for starting purposes. (See pages 40 
and 41) 

Starting Compensator or Auto Starter 

A device, used in starting induction motors by voltage 
control, consisting of a transformer combined with a suitable 
switching arrangement. (See page 39) 


6 


OPERATION 


The following types of electric machines are used 
in telephone work: 

DIRECT CURRENT MOTORS. 

ALTERNATING CURRENT MOTORS. 

DIRECT CURRENT GENERATORS, used for charging 
storage batteries, operating message registers and coin 
collector apparatus. 

ALTERNATING and PULSATING CURRENT RINGING 
GENERATORS. 

DIRECT CURRENT MOTORS 

A. Line and Battery Driven Motors. 

To Start 

1. See that starting box arm is in open circuit posi¬ 

tion. 

2. Remove insulating fibre stops from switch jaws. 

3. Move starting box arm to first contact, as indicated 

by mark on face of board. 

4. Close motor switch. If motor fails to start, open 

switch and investigate. 

5. Turn starting box arm slowly until it engages 

holding magnet. If the holding magnet fails, 
open switch. Never open the motor circuit by 
permitting the lever arm to return to open circuit 
position with switch closed. 

To Stop 

1. Open motor switch. 

2. See that starting box arm returns to open circuit 

position. 

3. Replace insulating fibre stops in switch jaws. 


7 




B. Battery Driven Ringing Motor with Combined 
Starting Box and Field Rheostat. 

To Start 

1. See that starting box arm is in open circuit po¬ 

sition. 

2. Remove insulating fibre stops from switch jaws. 

3. Move starting box arm to first contact, as indi¬ 

cated by mark on face of board. 

4. Close motor switch. If motor fails to start, open 

switch and investigate. 

5. Turn starting box arm slowly until it engages 

holding magnet. If the holding magnet fails, 
open switch. Never open the motor circuit by 
permitting the lever arm to return to open cir¬ 
cuit position with switch closed. 

6. Continue to turn hand wheel until the proper alter¬ 

nating current voltage is reached, or to the point 
indicated corresponding to the battery voltage. 

To Stop 

1. Open motor switch. 

2. See that starting box arm returns to open circuit 

position. 

3. Replace insulating fibre stops in switch jaws. 

ALTERNATING CURRENT MOTORS 

A. Small Alternating Current Motors with No Start¬ 
ing Device or with Automatic Starting Device 
in Motor. 

To Start 

1. Remove insulating fibre stops from switch jaws. 

2. Close motor switch. 

To Stop 

1. Open motor switch. 

2. Replace insulating fibre stops in switch jaws. 

8 


B. Motors with Starting Compensator or Auto 
Starter. 

(A) DRY TYPE WITH DOUBLE THROW SWITCH. 

To Start 

1. Remove insulating fibre stops from switch jaws. 

2. Close switch on side marked “Start”. 

3. When the armature has reached normal speed 

(which can be determined by the sound) throw 
switch quickly from the “Start” position to the 
other side marked “Run”. The switch must not 
be closed on the “Running” side before the arm¬ 
ature has reached normal speed, nor allow r ed to 
remain in “Starting” position after normal speed 
has been reached. 


To Stop 

1. Open motor switch. 

2. Replace insulating fibre stops in switch jaws. 

(B) OIL IMMERSED TYPE WITH HAND WHEEL OR 
LEVER. 

To Start 

1. Turn hand wheel or lever to “Start” position. 

2. When armature reaches full speed, not before, 

turn hand wheel or throw lever quickly to “Run” 
position. 


To Stop 

Turn hand wheel or lever quickly but carefully to 
“Off” position. 

NOTE: When auto starter is equipped with no voltage 
release, press push button to stop; and note 
that lever returns to “Off” position. 


9 





C. Alternating Current Motor with Switch and Start¬ 

ing Box. 

To Start 

1. Remove insulating fibre stops from switch jaws. 

2. Close motor switch. 

3. Turn starting box arm slowly until held by the 

clutch. 

To Stop. 

1. Open motor switch. 

2. Release starting box arm. 

3. Replace insulating fibre stops in switch jaws. 

D. Alternating Current Motor with Split Phase 

Starting Box. 

(A) EQUIPPED WITH SWITCH. 

To Start 

1. Remove insulating fibre stops from switch jaws. 

2. Close motor switch. 

3. Turn starting box arm slowly to “Start” position. 

4. When armature reaches full speed, not before, 

turn arm back slightly toward “Off” position so 
as to release clutch, and then quickly to “Run” 
position. 

To Stop 

1. Open motor switch and note that lever arm of 

starting box returns to “Off” position. 

2. Replace insulating fibre stops in switch jaws. 

(B) WITHOUT SWITCH. 

To Start 

1. Turn starting box arm slowly to “Start” position. 

2. When armature reaches full speed, not before, 

turn arm back slightly toward “Off” position so 
as to release clutch, and then quickly to “Run” 
position. 

To Stop 

1. Operate manual release and note that lever arm of 
starting box returns to “Off” position. 


10 



DIRECT CURRENT GENERATORS 


Charging Generators 

To Start 

1. Start motor or gas engine which drives generator, 

as described under “Motors" or “Gas Engines". 

2. See that generator brushes are making contact 

with commutator. 

3. Close circuit breaker. 

4. Read battery voltage. 

5. Remove insulating fibre stops from switch jaws. 

6. Manipulate generator field rheostat to obtain a 

generator voltage about one volt higher than 
voltage of battery. 

7. Close generator switch and charging transfer 

switch, where provided, and regulate current by 
manipulating field rheostat. 

In case of small batteries equipped with charging 
rheostats, current should be regulated by adjust¬ 
ing both rheostats. 

To Stop 

1. Adjust generator field rheostat until current is 

reduced to nearly zero. 

2. Open circuit breaker. 

3. Open generator switch. 

4. Turn rheostat arm until all resistance is cut in. 

5. In the case of the gas engine charging sets raise 

brushes from commutator, if style of holder per¬ 
mits. 

6. Stop motor or gas engine, as described under 

“Motors" or “Gas Engines". 

7. Replace insulating fibre stops in switch jaws. 

GENERATOR CAPACITY 

In offices where the maximum required generator output 
cannot be supplied by one generator without exceeding its 


11 





rated capacity in amperes, the power plant supervisor shall 
determine under what conditions and to what extent, if any, 
the rated capacity shall be exceeded, and under what condi¬ 
tions two generators shall be operated in parallel. 

PARALLEL OPERATION 
To Start 

1. Start one charging generator, as described above, 

and regulate current to about 20 amperes. 

2. Start second charging generator and regulate in 

same manner as first, giving particular attention 
to reading of battery voltage, which will be 
higher than when starting first generator. 

3. Regulate current of generators so that each fur¬ 

nishes its proper share of total generator output. 
If charging units are equal in capacity and are 
connected to same source of power each gener¬ 
ator should carry 50 per cent, of total output. 
If charging units differ in capacity or are con¬ 
nected to different sources of power, a different 
proportion may be more efficient. 


To Stop 

1. Adjust current of each generator to about 20 

amperes. 

2. Stop first one generator and then the other as 

described above. 

Message Register and Coin Collector Generators 

To Transfer Load from one Generator to Another 

1. Start motor which drives generator to be cut into 

service as described under “Motors”. 

2. Manipulate regulating rheostat to obtain same volt¬ 

age as obtained on generator in operation. 

3. Remove insulating fibre stops from generator 

switch jaws. 


12 


4. Close generator switch, throwing both generators 

in parallel, except where machine has failed or 

trouble developed. 

NOTE: In case a machine fails, open its generator 
switch before closing generator switch 
of machine to be cut in service. 

5. Open generator switch of generator which is to he 

cut out of service. 

6. Replace insulating fibre stops in switch jaws. 

7. Stop motor connected to generator which has been 

cut out of service, as described under “Motors”. 

ALTERNATING CURRENT GENERATORS 
Ringing Generators 

To Transfer Load from one Generator to Another 

1. Start motor w r hich drives generator to be cut into ser¬ 

vice, as described under “Motors”. 

2. If ringing set is provided with a regulating device adjust 

ringing voltages to their normal value. 

3. Throw over secondary switches. 

4. Stop motor connected to generator to be cut out of 

service, as described under “Motors”. 

When exchange load is transferred from one ringing ma¬ 
chine to another, “A” and “B” board ringing current, tone 
test, out of order, busy back, etc., shall be tested to insure 
accuracy of operation. A head receiver shall be used for 
making this test. 

RESERVE SETS 

Reserve sets shall be operated so as to carry the Central 
Office load at least two hours each week. Careful attention 
should be given to commutators, brushes and bearings. It may 
be necessary in some central offices to operate charging sets 
while test on ringing and message register sets is being made, 
so as to avoid excessive battery discharge. 


13 




POWER APPARATUS IN THE HANDS OF 
WESTERN ELECTRIC COMPANY 


A. Power Apparatus In the Hands of Western Electric Com¬ 
pany for Repairs will be tagged as follows: 

1. “Out of Service”. 

2. “Do not use except in case of emergency”. 

3. “Should be used. Under observation by Western Elec¬ 

tric Company.” 

Western Electric Company’s representative will, in all cases, 
call wire chief’s attention to the tag. 

Apparatus with a #3 tag attached shall be used according 
to regular routine, and defects which develop shall be noted 
and reported to the office. 


B. Power Plant Installation or Extensions by the Western 
Electric Company, from the time put into service until 
accepted by Telephone Company, will be tagged as fol¬ 
lows : 

“Notice to Wire Chief: Power apparatus listed below is 
in the hands of the Western Electric Company. It is 
available for use and the Telephone Company is ex¬ 
pected to care for ordinary routine maintenance. 

“Report to Engineering Department, via usual channels, 
any conditions involving special maintenance or re¬ 
pairs.” 

The apparatus listed on the tag shall receive ordinary 
maintenance of a routine character. 

If trouble is experienced or conditions arise which seem 
to be due to inherent defects in the apparatus, or faulty 
installation, or where conditions arise which would in¬ 
volve maintenance of a special character, the case shall 
be referred to the office before work is done to remedy 
the conditions, unless the telephone service is jeopar¬ 
dized, in which case the trouble shall be cleared and a 
report made as soon as possible. 


14 


TROUBLES 


Failure of Outside Power 

In case of failure of outside power the reserve machines 
shall be started in the following order: 

1. Ringing Set. 

2. Message Register Set. 

3. Coin Collector Set. 

4. Charging Set. 

MOTORS 

Failure to Start may be due to: 

• 1. Failure of outside power. 

2. Loss of one or more phases of a two or three phase 
circuit. 

8. Open fuse. 

4. Brushes not making contact with commutator. 

5. Open armature circuit. 

6. Open field circuit. 

7. Open starting box. 

GENERATORS 

Failure to Build up Voltage when Starting may be due to: 

1. Poor contacts of brushes with commutator. 

2. Open armature or field circuit. 

3. Loss of residual field magnetism (if self exciting). 

Reversed Voltage may be due to: 

1. Reversed connections. 

2. Reversed residual field magnetism (if self exciting). 

Loss or Reversal of Residual Field Magnetism of a Charging 
Generator may be remedied as follows: 

1. Raise or insulate all brushes from commutator. 

2. -Close circuit breaker. 

3. Close generator switch for a few seconds to allow bat¬ 
tery current to flow through field coils. 

4. Open circuit breaker and generator switch, restore 
brushes and start generator as described under 
“Charging Generators”. 


15 










Loss or Reversal of Residual Field Magnetism of a Message 
Register or Coin Collector Generator may be remedied 

as follows: 

1. Remove or insulate all brushes from commutator. 

2. Close generator switch for a few seconds to allow cur¬ 

rent from the generator which is running to flow 
through the field coils. 

3. Open generator switch, restore brushes and start gen¬ 

erator as described above. 

In case of Failure of All Machines, if Reversed, the polarity 
may be corrected temporarily by reversing the gen¬ 
erator armature leads at the connecting block or 
machine. 

Interruption of Message Register Current for a short period 
before another machine is thrown on the circuit, may neces¬ 
sitate requesting the Traffic Department to release all 
register keys to prevent the starting box from tripping on 
an overload. 

Variation in Load, indicated by fluctuating ammeter or volt¬ 
meter needle, may be due to poor brush contact of motor 
or generator, or to poor connection or partial open in arma¬ 
ture or field circuit. 

An Open Armature Coil can generally be located by a careful 
inspection of the commutator bars, as the excessive spark¬ 
ing will pit the bars in which the broken coil terminates. 

A Short-circuited Field Coil may be detected by its remaining 
cool while the others heat up excessively. 

Streaks of Fire on Commutator indicate presence of conductive 
material between segments. 

Heavy Load on Ringing Machine due to cable failure may be 
relieved by unscrewing resistance lamps of circuits in 
trouble. 

In case of Total Failure of all Ringing Machines emergency 
ringing circuits shall be established with another office. 


16 


Overheating of Bearings may be due to: 

1. Excessive belt tension. 

2. Failure of oil rings to revolve. 

3. Rough bearing surface. 

4. Bent shaft. 

5. Insufficient amount or poor grade of oil. 

6. End thrust due to improper levelling. 

7. Improper alignment. 

8. Large unbalanced magnetic pull due to the armature 

not being central with the frame; generally resulting 
from excessive wear of the bearings. 

9. Oil grooves in journal box stopped up. 

10. Dirty oil or grit. 

Overheating of Commutator may be due to: 

1. Overload. 

2. Excessive brush tension. 

3. Excessive brush sparking. 

4. Brushes not being in proper position. 

NOTE: If commutator becomes excessively heated, the 
load should be thrown off and machine stopped at once. 
Sparking may be due to: 

1. Oily or dirty commutator. 

2. Brushes not properly adjusted. 

3. Brushes burned on the ends. 

4. Rough commutator. 

5. A high, low, or loose commutator bar. 

6. High mica between segments. 

7. Open circuit in armature winding or conductors. 

8. Loose connections of armature conductors. 

9. Crossed armature windings or commutator segments. 

10. Copper picked up by the brushes. 

Excessive Field Heating may be due to: 

1. Rocker arm out of proper position. 

2. Overload (this may be due to inaccurate ammeter). 

3. Low primary or motor voltage, which would be indi¬ 

cated by decrease in speed. 

4. Abnormal generator voltage caused by circuit breaker 

opening, or all resistance of rheostat in battery #2 
charging circuit being cut in. 

17 






Throwing or Leaking of Oil may be due to: 

1. Oil too high in bearings. 

2. Shaft not level. 

3. End plate on the bearing not properly sealed. 

Machine Noise on the Battery may be due to: 

1. Poor brush contact. 

2. Sparking at brushes. 

3. Dirty commutators on charging generators or battery 

driven sets. 

4 . Slipping of belt. 

6. Loose connections. 

6. Improper location of brushes. 

CARE AND MAINTENANCE 

Cleaning Machines 

Machines and power apparatus shall be kept clean and in 
good repair at all times. With the exception of commutators, 
machines shall not be cleaned while in motion, but shall be 
cleaned immediately after shutting down, while in a heated 
condition. 

Charging Sets 

At the end of each run the set shall be cleaned as follows: 

1. Dust all parts. 

2. Clean commutators. 

3. Clean seats of brushes. 

4. Wipe off shaft to prevent oil creeping on commutator 

or armature. 

On alternate weeks each set shall receive a thorough clean¬ 
ing which, in addition to the above, shall be as follows: 

1. Blow out, with an air blast or bellows, the space 

between the tangs of commutators not enclosed, 
to remove dirt and copper dust. 

2. Reseat carbon brushes, where used, if necessary. 

(See Carbon Brushes page 22) 

In Offices where Three Charging Sets are installed, two sets 
shall be thoroughly cleaned in one week and the other 
set on alternate weeks. 


18 


Message Register Sets 

One set shall be cleaned daily as follows: 

1. Dust all parts. 

2. Wipe off shafts and commutators. 

3. Clean and, if necessary, reseat brushes. 

Ringing Generator Sets 

One set shall be cleaned daily as follows: 

1. Dust all parts. 

2. Wipe off shafts and commutators. 

3. Clean and, if necessary, reseat brushes. 

4. Polish collector rings and interrupters. 

Coin Collector Sets 

One set shall be cleaned daily as follows: 

1. Dust all parts. 

2. Wipe off shafts and commutators. 

3. Clean and, if necessary, reseat brushes. 

Reserve Sets 

The reserve message register, ringing generator and coin 
collector sets shall be cleaned as explained under the re¬ 
spective headings above and as follows: 

1. Where covers are provided, once a week. 

2. Where covers are not provided, on alternate days. 

Commutators 

While in motion, commutators shall be cleaned hourly or 
oftener with cheese-cloth, not waste, slightly moistened with 
kerosene to which an equal quantity of dynamo oil has been 
added. The cloth should be held against the commutator 
with some force. Where carbon or graphite brushes are used 
the commutator should then be wiped dry with a clean cloth. 

Special care should be taken to prevent oil from getting 
on the commutator except as above. Commutator compounds, 
commutator pastes, vaseline or paraffine shall not be used. 
A commutator shall not be smoothed with a file or emery 
cloth. In general, sand-paper shall not be used except under 
direction of power plant supervisor. 


19 



With proper care, a commutator should have a smooth 
highly burnished surface of a color somewhat similar to 
blued steel. 

A commutator should run without vibration and should not 
heat excessively. 

NOTE: The specified temperature limit of a commutator 
is 158° F. 

Turning down, sanding and repairing commutators shall 
be handled by the power plant force unless otherwise directed. 

Interrupter and Collector Rings 

Interrupter and collector rings of ringing generators shall 
be kept polished by use of an approved burnishing paste. 

Care should be exercised to prevent oil getting on inter¬ 
rupter and collector rings. 

Fibre and brass gear wheels shall be lubricated by 
means of vaseline but in the case of the fibre wheels only a 
small quantity shall be used, as an excessive amount is liable 
to soften the fibre. 

The enclosed gears of the SC type interrupter shall be 
lubricated by means of dynamo oil. 

Brushes and Brush Holders 

Brushes shall be properly seated to insure good contact 
with commutators. 

The spring tension shall be uniform, and sufficient to insure 
easy riding contact. 

Excessive spring tension shall be avoided as it has a 
tendency to overheat the commutator. 

Brushes shall not be removed nor any work done on the 
brush holders that would cause the brushes to become dis¬ 
placed, while the machine is in motion. 

Metal Brushes 

When cleaning, metal brushes shall not be removed from 
the holder; they shall be snapped upon the commutator to 
loosen the dust, which shall then be blown away. 


20 


Seats of metal brushes shall be cleaned by wiping with 
cheese-cloth moistened with kerosene and, if necessary, by 
scraping lightly in the direction of rotation to remove the 
coating of oil and dust. Sandpaper shall not be used. 

Seating, staggering and cutting of metal brushes will be 
done by the power plant force unless otherwise directed. The 
following method shall be used: 

The brushes should first be spaced and set. Then cut a 
piece of sandpaper (#iy 2 ) the width of the commutator and 
of a length sufficient to go around the commutator and meet 
with a butt joint. The sandpaper should be drawn tightly 
around the commutator, sand side out, and held in place by 
means of Le Page glue applied to the commutator at the 
joint. The paper should be held in place by twine wrapped 
around the commutator until the glue has hardened. The 
brushes should then be lowered on to the sandpaper. The 
pressure of the brushes should be about the same as when 
in regular service. The armature should then be revolved at 
normal speed until the brushes have been sanded on their 
entire contact surface. The brushes should then be raised 
and the sandpaper and glue removed from the surface of the 
commutator and the latter thoroughly cleaned. A cloth 
moistened with water should be used to remove the glue. 
The machine should be carefully cleaned, all copper dust 
being removed by blowing and wiping. The contact surface 
of the brushes should be wiped off with a cloth moistened 
with kerosene so as to remove any particles of grit which 
may adhere to the brushes. 

The armature of a machine equipped with metallic brushes 
shall not be turned backwards while brushes are in contact 
with commutators, as this operation will injure the brushes. 

Carbon Brushes 

Carbon brushes in reaction holders may be removed but 
care shall be taken to replace each brush in its original holder. 

Carbon brushes shall be reseated by drawing a strip of 
#00 sandpaper back and forth under brush with sand side 
next to brush, holding paper to surface of commutator so that 


21 



contact surface of brush will conform to curvature of commu¬ 
tator. The last few strokes of the sandpaper shall be in 
direction of rotation only. In no case shall brushes be 
scraped. (See page 42) 

To avoid chipping, carbon brushes shall be slightly bevelled 
at the toe. Copper plating on carbon brushes shall at all 
times be cut back 1/16" from commutator surface. 

The different sets of brushes shall be set at equal distances 

around the commutator. All brushes of a set shall cover the 

| 

same segments and each set shall cover the same number of 
segments. The proper number depends on the type of ma¬ 
chine and for charging generators is indicated in the following 
table: 

Minimum No. 



Type 




Range of 

of Segments 

No. of 

and 




Speed 

to be Cover¬ 

Poles 

Size 

Watts 

Volts 

Amps. 

R.P.M. 

ed by Brush 

4 

Ml 

750 

30 

25 

1700-1950 

2 % 

4 

Ml 

1,050 

42 

25 

1700-1950 

2V 2 

4 

M2 

1,500 

30 

50 

1700-1950 

2% 

4 

M2 

2,100 

42 

50 

1700-1950 

2% 

4 

M3 

3,000 

30 

100 

1100-1200 

3 

4 

M3 

3,000 

30 

100 

1700-1800 

3 

6 

M4 

5,250 

30 

175 

1100-1250 

2 

6 

M5 

6,750 

30 

225 

1100-1250 

2 

4 

M5 Yz 

9,000 

30 

300 

1100-1200 

6 

4 

M5 y 2 

12,000 

30 

400 

1100-1200 

6 

4 

M7 

18,000 

30 

600 

850-925 

5 

6 

M8 

24,000 

30 

800 

850-975 

4 

6 

M9 

30,000 

30 

1000 

475-500 

6 


The rocker arm shall be set so that the brushes make con¬ 
tact at the non-sparking points. These are designated by 
suitable markers on the rocker arm and on frame of machine. 

The rocker arm controlling position of brushes on machine 
shall not be moved outside of markers above referred to 
without special permission from Wire Chief. All such cases 
shall be referred to the power plant supervisor. 


22 


Each alternate set of brushes shall be so adjusted or stag¬ 
gered with respect to the others that brush contact is evenly- 
distributed over the whole commutator surface, thereby- 
distributing or reducing wear of commutator. (See page 26) 


Bearings 

Only approved grades of lubricating oils shall be used, a 
sufficient stock of which shall be kept on hand at all times. 

Special care shall be taken to prevent grit or any other 
foreign substance from entering bearings, oil cups or oil cans. 

Oil cups and reservoirs shall be kept filled to proper level 
and air hole in gauge kept open. 

Oil rings shall be inspected daily, immediately after machine 
is started, to see that they are revolving freely. 

Special care shall be exercised to avoid leakage of oil due 
to overfilled reservoirs or other causes. Continued leaking 
shall be reported to Wire Chief. 

Bearings shall be observed hourly or oftener to detect 
excessive heating. 

In case a hot bearing develops the load on the machine 
shall be taken off and, if possible, the speed reduced. The 
bearing should then be flushed with dynamo oil until cool. 
The set should in no case be stopped unless there is danger 
of the armature striking the pole pieces. 

Ringing machine interrupters, with hollow shaft oiling de¬ 
vice, shall be lubricated with clean, pure, vaseline made as 
soft as can be handled by adding dynamo oil. Once a month 
the shaft shall be carefully cleaned out and filled with new 
lubricant, special precautions being taken to prevent anything 
entering which could stop up the small opening from the 
hollow shaft to the bearing. 

Machine Covers 

Whenever practicable, two men shall be used in replacing 
machine covers, on account of the liability of breaking field 
wires. Machines shall not be entirely covered until they 
are cooled off. 


23 


Painting 

Paint shall not be applied to any part of the power plant 
without permission from the power plant supervisor. 

Power Switchboard and Fuse Panels 

Under no circumstances shall instrument seals be broken 
or ammeter shunt leads repaired by the central office force. 

Slate panels shall be cleaned periodically with bone black 
mixed with an approved cleaning oil. 

Inspection of Power Board Connections 

Inspection of all connections on the power board shall be 
made annually by the power plant force. 

Circuit Breakers, Starting Boxes, Rheostats, Etc. 

The contacts of circuit breakers, starting boxes, rheostats, 
voltmeter switches and switch blades shall be cleaned weekly; 
this to insure good contact and to prevent heating. Cheese¬ 
cloth slightly moistened with kerosene shall be used. In 
some cases it may be necessary to use crocus cloth, but in 
no case shall anything coarser be used. Special care shall 
be taken to protect lacquered surfaces. 

Circuit Breakers in Charging Circuits 

1. Operation. Circuit breakers in storage battery charg¬ 

ing circuits shall be set to operate on reversed current 
and on an overload current not greater than the 
capacity of the generator nor greater than the rated 
capacity of the smallest fuse in the circuit. The 
overload current at which it should operate shall be 
marked on or near each circuit breaker. 

2. Test. Circuit breakers shall be tested weekly as fol¬ 

lows: 

(a) Overload. While charging, increase generator 
output to the value marked on or near circuit 
breaker. Circuit breaker should operate at 
this point. 


24 


(b) Reverse Current. While charging reduce gen¬ 
erator output to zero. When needle indicates 
slightly below zero, if circuit breaker fails to 
operate automatically trip breaker at once by 
hand. 


Starting Boxes 

Test. Starting boxes shall be tested weekly as follows: 

(a) No Voltage Release. While the motor is run¬ 

ning, open motor switch and observe action. 
Starting box arm should release and return to 
open circuit position before motor stops. 

(b) Overload Release. While the motor is running, 

lift armature of overload device and observe 
action. Armature should be pulled up and held 
by the coil and motor should stop. Starting 
box arm in some types will release and return 
to open circuit position; in other types an 
auxiliary arm operates and opens circuit. 
After making test, motor switch shall be 
opened. 

(c) Note that armature of overload device is set at 

point indicated by white mark on plate. 

(d) Inspect contacts and connections. 

NOTE: In making tests of circuit breakers and start¬ 
ing boxes as described above a failure to 
operate properly shall be immediately re¬ 
ported to Wire Chief. 


Rheostats 

Rheostats shall be inspected weekly to see that movable 
and stationary contacts are in good condition, that they make 
good contact and do not heat excessively. Handles shall turn 
freely and arrows indicate correctly. 


25 







V- 

C3 


c3 

3 



Fig. 1. Staggering of Brushes. 

(See pages 1 and 23) 


26 



















Circuit Breaker 


a> 



Fig. 2a. Circuit Breaker with Polarized Relay. 
(Overload and reversed current protection) 

(See pages 2 and 3) 


27 














































Circuit Breaker 





(See pages 2 and 3) 


28 




























Circuit Breaker 



(See pages 2 and 3) 


29 























ToVoltmeter Switch 




Fig. 3. Coin Collector Generator. 

(See page 3) 


30 










































ToVoltm«t«r Switch 


<£> 


1 1 



Fig. 4. Message Register Generator. 

(See page 3) 


31 



































Field 



Fig. 5a. Ringing Generator. 
(Alternating and pulsating ringing currents) 

(See page 3) 


32 





































Self Excited 
Ringing Generator 



Fig. 5b. Ringing Generator. 
(Superimposed ringing) 

(See page 3) 


33 








































Fig 



6. Differentially Wound Motor. 

(See page 4) 


34 


























Shunt Field 

vwvv 



Fig. 7. Shunt Wound Motor. 

(See pages 4 and 6) 


35 



























To Switch^ ^To Field 



36 





































o 



Fig. 9. Compound Rheostat. 

(See page 6) 


■° -5 

"O O 

CU >j— 

"S "c 

^ ft. 

S- £= 


£ £ * 
a cz <3 


37 


Coarse Regulation Fine Regulation 



















Fig. 10. Combined Starting Box and Field Rheostat. 

(See page 6) 


38 
































































Fig. 11. Connections of Oil Immersed Auto Starter or 
Compensator. (2 or 3 phase motor.) 

(See page 6) 


39 




































































Fig. 12. Single Phase Motor with Split Phase Starting Box. 

(See page 6) 


40 








































QJ 

c 



Fig. 13. Single Phase Motor with Split Phase Starting Box. 
(For motors of less than 1 horse power) 

(See page 6) 


41 
























































Fig. 14. Seating Carbon Brushes. 

(See page 22) 


42 

















Fig. 15. Charging Circuit. 


43 


Dlscfiarge lead 


































































MERCURY ARC RECTIFIER SETS 


DEFINITIONS 

Anode 

The terminal at which the current enters the rectifier tube. 
Cathode 

The terminal at which the current leaves the rectifier tube. 
Compensating Reactance 

The reactance coil connected directly across the alternating 
current supply leads to maintain the arc in the rectifier tube. 
This reactance also serves to obtain an approximate adjust¬ 
ment of the a.c. voltage and current. 

Controlling Reactance 

The reactance connected in series with the alternating 
current lead for regulating the alternating current voltage 
supplied to the tube. Indirectly, it also regulates the direct 
current voltage while the rectifier is in operation. 

Insulating Transformer 

A one to one or two to one transformer used to insulate the 
rectifier circuit from the outside power circuits. 

Rectifier 

A device for converting an alternating current to a direct 
current. 

Rectifier Tube 

An exhausted glass vessel with four terminals. Two ter¬ 
minals are fitted with graphite electrodes and are termed 
anodes, one terminal is immersed in mercury and is called 
the cathode, the remaining terminal is also immersed in 
mercury and is used for the starting anode. 

Regulating Compensator —See Controlling Reactance 


44 


DESCRIPTION 


A Mercury Arc Rectifier Set Consists Essentially of: 

1. A rectifier tube, which contains a small quantity of 

mercury in vacuum and has four terminals. (See 
page 51) 

2. A compensating reactance. 

3. An insulating transformer. 

4. Switches; circuit breakers; resistances; choke coil, 

etc., varying with the type of rectifier. 

The action of the Mercury Arc Rectifier is based on the 
fact that the mercury in the rectifier tube when in a state 
of excitation gives out mercury vapor. This vapor affords a 
path for positive current to the mercury; but, if the current 
is reversed, the excitation ceases. 

The tube is provided with two terminals (or anodes) which 
connect with the two sides of the alternating current supply 
lead; and, consequently, when the supply current alternation 
makes one anode negative, the other anode becomes positive, 
and vice versa. 

The excitation of the mercury would not continue, however, 
unless some means were provided to maintain the current 
flow when the positive wave at one anode has decreased and 
is reversing and increasing to a positive wave at the other 
anode. The means provided consists of a compensating reac¬ 
tance coil bridged across the anodes—the battery under 
charge being connected between the mercury terminal (or 
cathode), and the middle point of the reactance coil. As the 
current alternates, first one anode and then the other becomes 
positive. The current flows from the positive anode through 
the mercury vapor to the mercury terminal, thence through 
the battery and one-half of the reactance coil to the opposite 
side of the supply lead, completing the circuit. 

Half of the compensating reactance is charged while this 
current flows through it, and, while the polarity of the alter¬ 
nating wave is decreasing, reversing and increasing to the 
opposite polarity, the reactance discharges. 

In this way, the reactance continues the current flow neces- 


45 



sary to maintain the arc in the rectifier tube until the voltage 
of each positive wave is high enough to maintain the current 
against the counter e.m.f. of the battery. It also increases 
the current value by means of the auto transformer action 
between the two halves of the reactance coil. 

To start the operation of the rectifier, a switch is provided 
to establish a temporary shunt circuit which is closed by a 
mercury bridge between the cathode and starting anode when 
the tube is tilted. When this bridge is made and broken by 
rocking, arcs are formed which vaporize sufficient mercury 
to start excitation. The alternate paths followed by the 
charging current when the rectifier is in operation are indi¬ 
cated by light and heavy arrows. (See page 51) 


OPERATION 

A. Old Type, with rectifier tube on front of switchboard, 
direct current regulating resistance, direct current 
switch, separate load and starting switches. 

To Start 

1. Examine the regulating switch to see that all re¬ 

sistance is cut in. This will be when the contact 
arm is on the extreme left contact. 

2. Remove insulating fibre stops from switch jaws. 

3. Close the alternating current switch. 

4. Close the direct current switch. 

5. Close the circuit breaker. 

6. Close the starting switch. 

7. Rock the tube gently with the hand. One flash 

should be sufficient to start the tube, but in cold 
weather more may be necessary. 

8. When the arc has started, wait about thirty seconds, 

then close the load switch. 

9. Open the starting switch. 

10. Adjust the direct current regulating resistance un¬ 
til the proper current is obtained. 


46 


To Stop 


1. Open the alternating current switch. 

2. Open the direct current switch. 

3. Open the load switch. 

4. Trip the circuit breaker. 

5. Cut in the direct current regulating resistance. 

6. Replace insulating fibre stops in switch jaws. 

B. Old Type, with single regulating switch. 

To Start 

1. Examine the regulating switch to see that all re¬ 

actance is cut in. This will be when the contact 
arm is on the extreme left contact. 

2. Remove insulating fibre stops from switch jaws. 

3. Close the alternating current switch. 

4. Close the circuit breakers. 

5. Hold the starting switch in the lower (starting)* 

position. 

6. Rock the tube gently by means of the hand-wheel 

on the front of the board. One flash should be 
sufficient to start the tube, but in cold weather 
it may be necessary to hold the starting switch 
in the lower position for about thirty seconds. 
NOTE: This time should not be exceeded as start¬ 
ing resistance may be damaged. 

7. Adjust the hand-wheel of the regulating reactance 

switch until the proper charging current is ob¬ 
tained. 

8. Restore the starting switch to the upper position. 

To Stop 

1. Open the alternating current switch. 

2. Trip the circuit breaker. 

3. Cut in the regulating reactance. 

4. Replace the insulating fibre stops in switch jaws. 


47 


C. New Type, with coarse and fine regulating reactance 
switch. 

To Start 

1. See that coarse regulating reactance switch is in 

proper position corresponding to desired direct 
current voltage. 

2. See that fine regulating reactance switch is in 

proper position, as left from previous charge. If 
doubtful, cut in all reactance by moving down 
the fine regulating switch as far as it will go. 

3. Remove insulating fibre stops from switch jaws. 

4. Close the alternating current switch. 

5. Close the circuit breakers. 

6. Hold the spring switch in the upper (starting) 

position. 

7. Rock the tube gently by means of the hand-wheel 

on front of board. One flash should be sufficient 
to start the tube, but in cold weather it may be 
necessary to hold the starting switch in position 
and rock the tube several times. 

8. Remove hand from spring switch, which will auto¬ 

matically throw into the lower (operating) po¬ 
sition. 

9. If necessary, adjust the charging current to the 

desired amperage by moving the fine regulating 
switch. 

To Stop 

1. Open the alternating current switch. 

2. Trip the circuit breakers. 

3. Replace insulating fibre stops in switch jaws. 


TROUBLES 

Failure to Obtain Arc may be due to: 

1. Failure of outside power, open fuses, or defective trans¬ 
former. 


48 


2. Cold weather; in which case efforts to start should be 

repeated several times as described under “To Start” 
for the proper type of rectifier. 

3. Low Charging Voltage. This may extinguish the arc 

when the load is thrown in, due to the counter e.m.f. 
of the battery being greater than the charging volt¬ 
age. If this happens, the voltage of the rectifier 
should be raised as described under “To Start”. 

4. Open circuit. Caused by spring clips becoming detached 

from rectifier tube terminals or wire from electrode 
to ferrule becoming unsoldered. 

5. Open circuit. Due to defective starting anode resist¬ 

ance. 

6. Defective vacuum of tube. This may be determined by 

noting the sound the mercury makes when allowed 
to roll gently about in the condensing chamber. If it 
makes a clear metallic click the vacuum is good, but 
if the sound is dull and the mercury sluggish in 
moving the vacuum is either partially or wholly de¬ 
stroyed. 


Failure to Carry Load may be due to: 

1. Drop in voltage of supply lead. 

2. Deterioration of rectifier tube. This may also be indi¬ 

cated by the tube having a smoked appearance; a 
new tube will then be necessary. 

3. Leaky rectifier tube. (See above—“Defective Vacuum”) 


Overheating of Starting Anode and Starting Anode Resist¬ 
ance, After Starting Switch is Opened, may be due to: 

A grounded connection at some point between the starting 
anode and starting switch. Normally, these carry current for 
a few seconds only and are out of circuit while the rectifier 
is in operation. 


49 




CARE AND MAINTENANCE 


Rectifiers shall be kept clean and in good repair at all 
times. Any defects, either in wiring, connections, resistances, 
tube or other parts shall be reported to the office. 

Cleaning 

Each week the set shall receive a thorough cleaning. This 
shall include the contacts of circuit breakers, rheostats and 
switches which shall be cleaned with cheese-cloth slightly 
moistened with kerosene oil. In some cases it may be neces¬ 
sary to use crocus cloth but in no case shall anything coarser 
be used. Special care shall be taken to protect lacquered 
surfaces. 

Slate panels shall be cleaned periodically with bone black 
mixed with an approved cleaning oil. 

An annual inspection shall be made during the first week 
in June of the oil in the oil-cooled transformer in the alter¬ 
nating current supply circuit. A written report of this in¬ 
spection shall immediately be forwarded to the office—stating 
whether or not oil is at the proper height, and noting any 
indication of deterioration in the quality of the oil. 

An annual inspection of the rectifier connections and ap¬ 
paratus will be made by the power plant force, who, at the 
same time, will attend to the transformer oil, changing oil 
if necessary. 

A spare rectifier tub,e should be held in reserve, and, in 
case the tube in service has to be replaced by the spare tube, 
a new one should be ordered immediately. 


50 


A.C.5upply 


Primary 


U VW\A/VW U 



51 























































GAS ENGINES 

The White and Middleton Special Electric Type 

DEFINITIONS 

Air Receiver 

A pipe connecting the mixing chamber with the air in the 
engine base. 

Connecting Rod 

The rod which connects the piston to the crank shaft, and 
changes the reciprocal motion of the piston into a rotary 
motion. 

Cooling Chamber 

That portion of the cylinder, between the inner and outer 
walls, in which the cooling water circulates. 

Crank Shaft 

A rotating shaft to which the power from the piston is 
transmitted by means of the connecting rod. 

Cycles 

The number of piston strokes between the intervals of 
ignition of the explosive mixture in the cylinder. 

NOTE: This engine is a four-cycle engine. 

Cylinder 

The chamber in which the piston moves. 

Exhaust Pipe 

A pipe which carries the burned gases from the cylinder. 
Exhaust Pot 

A chamber in which the exhaust gases expand. 

Expelling Valve 

A valve through which the burnt gases, left in the cylinder 
after the working stroke, are expelled. 


52 


Equalizer 

A device for regulating gas pressure. (See page 60) 

Governor 

A device which automatically controls the admission of the 
gas to the mixing chamber and thereby regulates the speed 
of the engine. 

Igniter 

A device attached to the cylinder and so constructed that 
an electric spark can be introduced into the cylinder for the 
purpose of igniting the mixture of gases. 

Induction Valve 

A valve through which the explosive mixture is admitted to 
the cylinder. 

Muffler 

A chamber or chambers for reducing the noise of the 
exhaust. (See page 64) 

Mixing Chamber 

A chamber in which air and gas mix before entering the 
cylinder. 

Piston 

The reciprocating part of the engine which, by means of the 
connecting rod, transmits to the crank shaft the power pro¬ 
duced by the expansion of the gases in the cylinder. 

Relief Valve 

A valve on the outside of the cylinder which, when open, 
relieves compression. 

Spark Coil 

A coil of high inductance for producing a spark when the 
circuit is broken. 

Water Jacket—See Cooling Chamber 


53 





DESCRIPTION 


A gas engine derives its power from the expansive force of 
gases produced by igniting in a closed cylinder a compressed 
explosive mixture of gas and air. The explosion is accom¬ 
plished by means of an electric spark which ignites the. mixture 
of gas and air, and raises the temperature to about 2,700° F., 
thus greatly increasing the pressure. This pressure acts on 
a movable piston in the cylinder and converts the force of 
the gases into mechanical energy. 

Starting with the piston at the head end, and the engine 
on the dead centre, as the balance wheels are revolved the 
piston moves toward the crank end and thus produces a 
vacuum in the cylinder, which opens the induction valve 
drawing gas and air from the mixing chamber through port 
“A” and induction valve “B” into the cylinder. (See page 63) 
Having reached the dead centre at the crank end, the piston 
starts to return and thereby compresses the mixture of 
gas and air and closes the induction valve “B”. Just before 
the piston has reached the end of its travel toward the head 
end, the igniter is operated and explodes the charge. This 
explosion forces the piston towards the crank end and when 
it has reached its extreme travel the main exhaust “F” being 
opened, allows a portion (about 90%) of the exploded mixture 
to pass from the cylinder through the main or port exhaust 
opening “F” into the exhaust pot, thus enabling the balance 
wheels to carry the engine past the dead centre and start the 
piston on its return toward the head end. During the return of 
the piston toward the head end, the expelling valve “C” is 
opened and the remainder of the exploded mixture (about 
10%) is expelled through valve “C” and the supplemental 
exhaust pot “D” to the exhaust pipe, thus emptying the 
cylinder. As the piston leaves its extreme position at the 
head end, the expelling valve should close and as it starts 
to return toward the crank end, the induction valve again 
opens and the operation is repeated. It will thus be seen 
that there is only one working stroke for two complete 
revolutions, during which the following events occur; 


54 


1. Admission of explosive mixture. 

2. Compression of explosive mixture. 

3. Explosion of mixture (working stroke). 

4. Exhaust. 

The reason for carrying the major part of the exhaust 
through the exhaust pot and muffler is to gradually bring the 
burnt gases down to atmospheric pressure before discharging 
them into the outer air, thus reducing the noise of the exhaust. 


OPERATION 

Before Starting, see that: 

1. Cover is removed. 

2. All parts are clean. 

3. Oil cups are full. 

4. All parts not oiled from cups are oiled. 

5. Cooling water is available. 

6. Brushes on generator are raised from commutator if 

holder permits. 

7. Punch on contact rod has side marked “Starting” up. 

8. Trip dog is thrown in. 

9. Battery switch is closed. 

10. Oil cups are feeding. 

11. Valves on service side of equalizer are open. 

12. Relief valve is open. 

13. Pointer on equalizer is at “On”. 

14. Gas valve at engine is open to starting position. 

15. Piston is at head end of cylinder. 

To Start 

» 

1. (a) Turn balance wheels over rapidly until explosion 

occurs. At starting, ignition should occur when 
the crank is about 12° above centre. (For direc¬ 
tion of rotation see page 61) 

(b) If engine is equipped with an air compressor, open 
valve until piston reaches end of stroke, then 
close air valve. 


55 





2. Close relief valve slowly. 

3. Close muffller and drip valves. 

4. When trip dog is released, turn punch quickly so that 

side marked “Starting” is down. When running, ig¬ 
nition should occur when the crank is about 15 & 
below centre. 

5. Open valves for circulating water. 

6. Lower generator brushes on commutator. 

7. Open gas valve at engine to running position. 

While Running, see that: 

1. Cooling water circulates properly. 

NOTE: Water from the cooling chambers should have 
a temperature of from 150° to 170° F. 

2. Oil is feeding properly. 

NOTE: Glass oil cups should feed 6 to 8 drops per 
minute. Cylinder oil cup should feed 10 to 
12 drops per minute and should be adjusted 
while cylinder is hot. 

3. Belt runs true on pulleys. 

4. Air compressor is operated until sufficient air has been 

compressed in tank to start engine for another run. 

Before Stopping, see that: 

1. Muffler and drip valves are open. 

2. Raise generator brushes if holder permits. 

To Stop 

1. Close valve on service side of equalizer. 

2. Close valve at engine. 

3. Open relief valve. 

4. Open battery switch. 

After Stopping, see that: 

1. Oil feeds are shut off. 

2. Cooling water valves are closed. 

3. All gas valves are closed. 

4. Piston is at end of cylinder and on compression stroke. 

5. All parts are clean and all bolts, nuts and screws are 

tight. 

6. Cover is replaced when engine is cool. 


56 


TROUBLES 


Failure to Start may be due to: 

1. Lack of igniting current. 

2. Lack of gas. 

3. Valves stuck. 

4. Choked exhausts or muffler. 

5. Defective igniter. 

Variation of Speed or Loss of Power may be due to: 

1. Sticking of valve in equalizer. 

2. Faults in governor mechanism. 

3. Poor tension of spring on gas inlet valve stem. 

4. Defective wiring in ignition circuit. 

5. Worn piston rings or piston. 

6. Worn valves. 

7. Improper adjustment of compound slide rod. 

8. Improper mixture. 

9. Slipping of belt. 

10. Defective igniter. 

Piston Sticking may be due to: 

1. Gummed or carbonized oil in cylinder. 

2. Defective ring or rings. 

Hot Cylinder may be due to: 

1. Improper lubrication. 

2. Improper water circulation. 

3. Carbon deposit on piston. 

4. Improper mixture. 

Backfiring may be due to: 

1. Premature ignition. 

2. Improper mixture. 

3. Overheated cylinder. 

4. Leaky gas inlet valve. 

5. Improper tension of induction valve spring. 

6. Sticking of induction valve. 

7. Carbon deposit or rough surface on piston or cylinder. 


57 



Knocking may be due to: 

1. Hot cylinder. 

2. Improper spark adjustment. Igniter points should be 

set about 1/32" apart. 

3. Disarrangement of engine parts such as loose wrist 

pin, loose brasses or worn bearings, etc. 

CARE AND MAINTENANCE 

Cleaning 

The engine shall be cleaned while it is warm. 

Repairs 

All repairs or adjustments of bearings, governor and mixing 
chamber valves shall be made by the power plant force or 
under instructions from the power plant supervisor. 

Belts 

Belts shall not be tightened or removed without permission 
from the power plant supervisor. Belts shall run so that the 
laps run from the pulley. (See page 62) 

Oily belts may be cleaned with whiting, powdered chalk, 
fullers’ earth or air slaked lime. Dirty belts may be cleaned 
with a scraper. 

NOTE: Belts shall not be cleaned while in motion. 

Oils 

Oils for engine use shall be approved by the power plant 
supervisor. 

Cylinder oil shall be used for the cylinder oil cup and 
governor gears; and dynamo oil for all other cups and bear¬ 
ings. 

In cold weather a few drops of dynamo oil in the saucer 
of cylinder oil cup will aid lubrication while starting. Too 
high a temperature in the cylinder is liable to burn the lubri¬ 
cating oil. The best grades of lubricating oil commence to 
burn at a temperature of 400° F. 

Supply oil can openings shall be suitably protected to pre¬ 
vent foreign matter entering. 


58 


Hot Cylinders or Bearings 

Overheated cylinders or bearings shall he flushed with the 
proper lubricating oil until cool. 

NOTE: Keep engine running slowly after removing load. 

Condensation 

Receptacles shall be provided to receive condensation from 
the muffler and drip valves. 

Air Compressors 

Air compressors shall be operated, while the gas engine 
set is being used for charging, until sufficient air has been 
compressed in the tank to start the engine for the next run. 







GAS INLET 



Fig. 17. Equalizer. 

(See page 53) 


60 















































































































































Fig. 19. Lap Joint of Belt. 

(See page 58) 


62 










E.XHAU3T POT 



Fig. 20. 

(See page 54) 


63 





































































































































































* 



Fig. 21. Muffler. 

(See page 53) 


64 























































EMERGENCY CHARGING SETS 

Portable Ferro Gasoline Engine Driven Generators 

DEFINITIONS 


Auxiliary Air Valve 

An adjustable valve at the bottom of the air intake chamber 
of the carburetter for automatically maintaining a constant 
mixture at various speeds. 

Carburetter 

The device which supplies the cylinder with vaporized gaso¬ 
line mixed with air. 

Combustion 

The burning of the gasoline vapor after ignition has taken 
place. 

Connecting Rod 

The rod which connects the piston to the crank shaft and 
changes the reciprocal motion of the piston into a rotary 
motion. 

Cooling Chamber 

That portion of the cylinder, between the inner and outer 
w'alls, in which the cooling water circulates. 

Crank Case 

The metal casting which encloses the crank shaft. 

Crank Shaft 

A rotating shaft to which the power from the piston is trans¬ 
mitted by means of the connecting rod. 


65 






Cycles 

The number of piston strokes between the intervals of 
ignition of the explosive mixture in the cylinder. 

NOTE: This engine is a two-cycle engine. 

Cylinder 

The chamber in which the piston moves. 

Exhaust Pipe 

A pipe which carries the burned gases from the cylinder. 
Governor 

A device which automatically controls the admission of the 
explosive mixture to the cylinder, and thereby regulates the 
speed of the engine. 

Induction Coil 

The coil which transforms the low tension battery or gener¬ 
ator current to a high tension current. 

Muffler 

A chamber for reducing the noise of the exhaust. 

Needle Valve 

A valve on the carburetter for adjusting the proportion of 
gasoline vapor in the mixture. 

Piston 

The reciprocating part of the engine which by means of the 
connecting rod transmits to the crank shaft the power pro¬ 
duced by the expansion of the gases in the cylinder. 

Priming of Cylinder 

Inserting gasoline to the cylinder through the cup on top. 

66 


Spark Plug 

A device attached to the cylinder and so constructed that 
an electric spark can be introduced into the cylinder for the 
purpose of igniting the mixture of gases. 

Timer 

A device for advancing or retarding the spark, so that the 
mixture in the cylinders may be ignited at a desired position 
of the piston stroke. 

Vibrator 

An attachment for making and breaking the primary circuit 
of the induction coils. 

Water Jacket—See Cooling Chamber 

NOTE: For explanation of electrical terms see section on 
“Motors and Generators”. 

OPERATION 

Before Starting, see that: 

1. Platform of truck is approximately level. 

2. Exhaust pipe is screwed into muffler. 

3. Hose is connected to inlet and outlet connections and 

also to the water supply and that water flows properly. 
The inlet connection is the lower one. If a barrel 
is used prime the inlet hose by pouring water in it 
till it is full and water runs out of the outlet connec¬ 
tion at the pump, then plunge the end of the inlet 
hose to the bottom of the barrel and place the outlet 
hose on top of the barrel in order to complete circu¬ 
lation of water. See that inlet connection is air 
tight. 

4. Oil shows in oil sight gauges of generator bearings. 

5. Oil is applied to the pump eccentric, timing gears and 

timing commutator. 


67 



6. Engine oil reservoir is full. Fill through, the standpipe 

and close the relief valve in its cap. 

7. Gasoline tank is full. 

8. Generator switch is open. 

9. Generator brushes raised from commutator. 

10. Charging leads are properly connected to switch ter¬ 

minals and central office charging bus bars. 

11. Ammeter and voltmeter leads are connected. 

12. Leads to the plug fuse cutout are reversed IF the nega¬ 

tive end of the central office storage battery is 
grounded. 

To Start 

1. Open water inlet. 

2. Open cock in gasoline feed pipe and prime carburetter 

by tapping priming float spindle. 

3. Open needle valve about one turn from closed position. 

4. Set timer to fully retard spark, as ignition should take 

place later than when running. 

5. Open compression relief cocks. 

6. Fill priming cups with gasoline; open priming cocks 

and rock fly wheel to draw charge into cylinders. 

7. Throw ignition switch to “B” (see designation on 

switch) to close dry battery circuit. 

8. Close priming cocks and crank the engine. 

9. The instant engine fires advance the spark and close 

compression relief cocks. 

10. Adjust needle valve until engine fires regularly and 

runs smoothly. 

11. Lower brushes on generator commutator. 

12. Adjust field rheostat, or speed of the engine by means 

of the timer, until generator voltage is about one volt 
higher than voltage of battery. 

13. Close generator switch and adjust field rheostat, timer 

and needle valve, until generator is delivering desired 
current and engine runs smoothly. 

14. Throw ignition switch to “M” (see designation on 

switch) to connect the ignition circuit to the genera¬ 
tor. Adjust small rheostat until engine is running 


68 


satisfactorily with the least possible sparking at the 
points of the vibrator. 

15. Readjust, if necessary, the field rheostat, timer and 
needle valve until generator is delivering desired 
current and engine runs smoothly. 

NOTE: 

(a) If the desired output cannot be obtained by means 

of the field rheostat adjustments, it can be ob¬ 
tained by speeding up the engine. This is done 
by advancing the spark. 

(b) When the engine is running, the needle valve of 

the carburetter should be closed as much as pos¬ 
sible without causing back firing. 

While Running, see that: 

1. Cooling water is circulating. 

2. All oil tubes of the engine are feeding properly 

(a) 6 drops a minute to the bearings. 

(b) ' 10 drops a minute to the cylinders. 

(c) 20 drops a minute to the carburetter. 

3. The pump eccentric, timing gears and timing commu¬ 

tators are oiled every half hour. 

4. Engine does not pound, miss fire or back fire; nor 

cylinders get too hot. 

5. Gasoline tank is kept well filled. 

6. Generator lubricating rings revolve properly. 

To Stop 

1. Reduce generator load. 

2. Open main switch. 

3. Shut off gasoline supply at tank and allow engine to 

run until the carburetter is empty. 

4. Open ignition switch. 

5. Open relief valve on top of engine oil standpipe. 

6. Raise brushes from generator commutator. 

7. Close needle valve. 

8. Shut off water. In cold weather, or if set is to be 

moved, disconnect hose and drain all water from 
water jacket of cylinders. 


69 




TROUBLES 


Failure to Start may be due to: 

1. Lack of igniting current. 

2. Lack of, or impure, gasoline. 

3. Dirty spark plug. 

4. Incorrect adjustment or fouling of needle valve of 

carburetter. 

E. Ignition taking place too late—in that case advance 
spark slightly. 

6. Excess of oil in crank case. This may be removed by 
unscrewing the drain plugs. 

Variation of Speed may be due to: 

1. Improper setting of rheostat in igniter circuit. 

2. Improper setting of auxiliary air valve. 

3. Too much gasoline—engine flooded. 

4. Obstruction in needle valve or in vent in filling hole 

plug of gasoline tank. 

Piston Sticking may be due to: 

1. Cylinder becoming gummed from oil. 

REMEDY: Prime the top of cylinder with half a cup¬ 
ful of kerosene followed by a tablespoon¬ 
ful of cylinder oil. Then turn engine 
over a few times. 

Hot Cylinders may be due to: 

1. Improper lubrication. 

2. Carbon deposit in cylinder. 

3. Insufficient or clogged water circulation. 

4. Retarded spark. 

5. Too rich a mixture. 

Missfiring may be due to: 

1. Defective spark plugs. 

2. Timing commutator cut or dirty. 

3. Vibrator out of adjustment. 


70 


Backfiring may be due to: 

1. Spark too far advanced. 

2. Too lean a mixture. 

Explosion in Muffler may be due to: 

1. Too rich a mixture. 

2. Loose connection in ignition circuit. 

Engine Knocking may be due to: 

1. Hot cylinder. 

2. Spark too far advanced. 

3. Disarranged or worn engine parts. 

4. Improper mixture. 

Inability to Develop Full Load may be due to: 

1. Only one cylinder firing. 

2. Defective spark plug. 

3. Defective, or poorly adjusted, timing commutator. 

4. Loose connection or open in the ignition circuit. 


CARE AND MAINTENANCE 


CAUTION 

Gasoline is a dangerous explosive. Keep all open flames, 
including lanterns, away from engine! 

Protection of Set 

In case of rain or snow, the set shall be suitably protected. 

Cleaning of Engine 

At the end of each run, the engine shall be cleaned as 
follows: 

1. Wipe all external parts clean and dry. 

2. Wipe unpainted parts with waste dipped in oil. 


71 


Cleaning of Generator 

At the end of each run, the generator shall be cleaned as 
described in the section on “Motors and Generators”. 

Covering 

When sufficiently cool, the set shall be covered with the 
tarpaulin. 

Hot Bearings 

Throw off load, reduce speed of engine and flush bearings 
with oil until cool. 

Master Vibrator 

Turn vibrator end for end once a day, or more often, to 
prevent pitting of contacts. 

Oil 

The proper oil to be used with the engine is “Gargoyle 
Marine Motor Oil” or an approved equivalent. 

Repairs 

Repairs shall be made only under the direction of the power 
plant supervisor. 

Before Shipment, see that: 

1. Gasoline tank is empty. 

2. Ignition switch is in “Off” position. 

3. All tools are locked in box. 

4. The two lengths of hose and the two charging leads 

are strapped inside the casing. 

5. Ammeter and voltmeter are removed from their mount- 

ing and placed in the carrying case. 

6. The two cans of lubricating oil are secured within the 

casing. 

7. The housing panels put in place and roof locked; by the 

two padlocks. 

72 


Mode of Shipment 


Unless otherwise specified by the Division Equipment En¬ 
gineer, the set shall be shipped as follows: 

1. The charging set by freight. 

2. The keys for the tool box, padlock, and instrument case 

by registered mail. 

3. The instrument carrying case by express. 


T ests 

A complete inspection, and full load test of at least two 
hours, shall be made bi-monthly under the direction of the 
power plant supervisor. A record of each inspection and 
test shall be entered in a log book to be kept in the tool 
box. A duplicate record shall be sent to the power plant 
supervisor. 


73 






Fig. 22. Portable Gasolene Engine Driven Charging 

Generator. 


74 








STORAGE BATTERIES 

The Electric Storage Battery Co. Type 
DEFINITIONS 

Battery Discharge 

That portion of the load which is carried by the battery. 

Bolt Connector—See Connector 

Bus Bar 

A lead bar, located between cells, to which the plates are 
burned. The terminal busses of the end cells are lead 
covered copper bars. 

Capacity, Rated 

The rated capacity of a battery is expressed in ampere 
hours and is equal to the normal rate in amperes, multiplied 
by eight (8) hours. 

For example, the rated capacity of a #51-G battery is 
500 x8 = 4000 ampere hours. 

Capacity, Reserve 

The difference between the rated capacity of a battery 
and the actual 24-hour discharge, expressed In ampere hours. 

Cell 

One complete unit of a battery. 

Charging Current 

That portion of the generator output which is in excess of 
that required by the load. 

Connector 

A lead covered bolt, generally used on type F and smaller 
cells, for connecting the elements to adjacent cells or to 
the external circuit. 


75 


Displacing Tank or Block 


A lead alloy tank, or treated wood block, placed in the 
pilot cell, when not fully equipped with plates, to fill the un¬ 
occupied space. 

Drip Pot 

A receptacle used to collect the condensation from the 
vent pipe. 

Electrolyte 

A solution, consisting of especially pure sulphuric acid and 
water, in which the plates are immersed. 

Floating 

The battery is said to be floating when the generator 
output and the load are approximately equal. 

Generator Output 

The total current furnished by the charging set. 

Hold-Down 

A glass weight for holding wood separators in position. 
Hydrometer 

An instrument for measuring the specific gravity of the 
electrolyte. The specific gravity of water being taken as 
1.000, a reading of 1.210 on the hydrometer indicates that 
the solution is 21% more dense than water. 

Insulator 

A glass support for tanks and wood sand trays. 

Level Indicator—See Marker 


76 


Load 


The current consumed by apparatus connected to the bat¬ 
tery. The current is supplied either by battery, charging 
generator, or both. 

Marker 

An indicator to show the proper level of the electrolyte. 

Pilot Cell 

That cell selected by the power plant supervisor to rep¬ 
resent the state of charge of the entire battery. 

Plate, Positive 

A plate of dark brown color consisting of buttons of active 
and reserve material supported in a lead alloy grid. 

Plate, Negative 

A plate of slate grey color consisting of a grid containing a 
number of rectangular openings filled with pure spongy lead. 

In the “Box Type” negative, the openings are covered with 
perforated lead sheets. In the “Pasted Type” negative, used 
with type D and smaller cells, excepting the type ET, the 
active material is pressed into the grid openings. 

Plate Support 

A sheet of glass, used with type F and larger cells, to 
hold the plates in position. 


Sand Tray 

A wood or glass tray filled with sand on which the glass 
jar rests. 

Sediment—See description on page 80. 


77 


Separator 

A specially treated wood diaphragm equipped with dowels, 
or a glass tube or a rubber strip, used to keep the plates from 
coming in contact with each other. 

Suiphation—See description on page 80. 

Terminal Cup 

A lead coated connector, provided on end bus bars, into 
which the conductors are sweated. 

Vent Pipe 

A lead or terra cotta duct for carrying the fumes from 
the battery room or casing to the outside air. 


DESCRIPTION 

Storage or secondary batteries, also called accumulators, 
consist of cells in which a chemical change is brought about 
by passing an electric current through them, thereby render¬ 
ing them capable of giving back electrical energy by dis¬ 
charging them until they return to their previous chemical 
condition. 

Each Cell of a Storage Battery Consists Essentially of: 

1. A negative group of plates (one or more). 

2. A positive group of plates (one or more). 

3. A lead lined wood tank or glass jar. 

4. The electrolyte or solution. 

Electrolyte 

The electrolyte in a cell in good condition, at full charge 
and at normal temperature, should have a specific gravity 
of about 1.210. While charging, the specific gravity rises; 


78 


and while discharging, it falls. As the change is propor¬ 
tional to the ampere hour charge or discharge, the specific 
gravity readings are used to indicate the state of charge 
or discharge. To eliminate errors, due to changes in tem¬ 
perature, specific gravity readings are taken with a hydrom¬ 
eter which is correct at 70° Fahrenheit and readings taken 
at other temperatures are corrected to that standard. It 
is important that the volume of electrolyte should be main¬ 
tained constant, in order that specific gravity readings may 
be properly compared, and for this purpose water must be 
periodically added as described on page 85. This is 
especially important in the pilot cell, as a difference of less 
than y & " in the level may make a difference of over an 
hour in charging. 

Chemical Action During Discharge 

The sulphuric acid in the electrolyte combines with the 
metallic lead in the negative plates, and with the peroxide 
of lead in the positive plates, forming lead sulphate on both 
plates. This form of sulphate is harmless and invisible. 
The separation from the electrolyte of the sulphuric acid, 
which enters into the formation of the lead sulphate, causes 
the lowering of the specific gravity during discharge. 

Chemical Action During Charge 

The chemical action which takes place while the battery 
is being charged is approximately the reverse of the above. 
The action of the electric current decomposes water in the 
electrolyte, the oxygen combining with the lead sulphate in 
the positive plates to form lead peroxide and sulphuric acid, 
and the hydrogen going to the negative plates, breaking up 
the lead sulphate into sulphuric acid and metallic lead. 
Thus, the active material becomes lead peroxide in the 
positive plates, and spongy pure lead in the negative plates. 
The decomposition of the water and the liberation of the 
sulphuric acid, caused by the conversion of the lead sul¬ 
phate on both plates, causes the rise of specific gravity 
during charge. 


79 


Formation of Gas 

As the cell approaches the charged condition, the active 
material becomes changed, as described above, and cannot 
absorb all of the hydrogen and oxygen produced. The excess 
passes off in the form of gas. 

Sulphation 

During the discharge, sulphate of lead is being formed, as 
explained under “Chemical Action”. If the cell is permitted 
to stand discharged for some length of time, is habitually 
undercharged, or otherwise neglected, the sulphate reaches 
a condition where it tends to fill the pores of the plates 
and to make the active material dense and hard. This 
form of sulphate cuts out of service those portions of the 
plate on which it is deposited. It is this condition which is 
ordinarily referred to as “sulphated”. 

Overcharge 

At regular intervals the charge is continued to a point 
where no further rise in specific gravity or voltage takes 
place. This overcharge is given for the purposes of: 

1. Converting to active material any harmful sulphate 

that may have formed. 

2. Stirring up the electrolyte thereby preventing strati¬ 

fication. 

Variation in Specific Gravity 

The actual amount of lowering of the specific gravity of 
the electrolyte, between full charge and complete discharge, 
is dependent upon the quantity of solution in the containing 
vessel, compared with the bulk of the plates. 

When the plates are badly sulphated or a large proportion 
of the active material has been lost, the range in the spe¬ 
cific gravity for a complete discharge is much reduced. 

Sediment 

In the normal use of a battery, active material, mostly 
from the positive plates, is gradually thrown off and settles 


80 


to the bottom of the cells in the form of sediment. Unneces¬ 
sary overcharging, resulting in excessive gassing, accelerates 
the wear on the plates and consequently the accumulation 
of the sediment. 

The sediment is a conductor and therefore must not be 
allowed to become so deep that it comes in contact with 
the bottoms of the plates, as it will short circuit them. 

Temperature of Battery Room 

To obtain the best results, the temperature of the battery 
room should be kept between 40° and 80° F. If the temper¬ 
ature is over 80° F. for any great length of time, the wear 
on the plates is excessive. If the temperature is low no 
harm results, but the available capacity is reduced during 
the period of low temperature. 

Voltage 

The voltage of a battery is affected by the rate of charg¬ 
ing or discharging. For that reason, the voltage cannot 

be used to indicate the condition of the charge without 
taking into consideration the rate. 

The following table gives the voltage per cell at different 
discharging rates below which it is not considered safe to 
allow a cell to drop: 

Voltage per Cell Discharging Rate 

1.85 Normal 

V<> % Normal 

1.93 V 2 Normal 

1.97 % Normal 

Normal Charging and Discharging Rate 

The rate in amperes specified by makers of the battery 
as the proper rate for charging, is known as the normal 
charging rate and is the same as the normal discharging or 
eight (8) hour rate, i. e., the rate which would completely 
discharge a fully charged new cell in eight (8) hours. 


81 


The following table gives makers normal 
plate for various types of plates: 

rate per positive 

Type of 

Approximate Size of Plate 

Amperes per 

Plate 

Not Including Lugs 

Positive Plate 

G 

15 5/16" x 15 5/16" 

20 

F 

11" xlO 1 /." 

10 

E 

7%" x 7%" 

5 

D 

6" x 6" 

2y 2 

C 

4%" x 4" 

I'A 

ET 

7%" x 7%" 

4 y 2 

PT 

8%" x 5" 

3 

CT 

5" x 5" 

iy 2 

BT 

4" x 3" 

% 


To find the normal rate of a battery, multiply amperes per 
positive plate, given in table, by the number of positive 
plates in a cell. For example, the normal rate of a battery 
type G-51, which has 25 positive plates per cell, is 25 x 20 = 
500 amperes. 

When 2 or more sets of cells are connected in parallel for 
charging, the total charging rate is the sum of the charging 
rates of each set. 


OPERATION 

The following instructions apply to central oflice or other 
batteries which are operated by the specific gravity method. 
For instructions covering two plate cells, see page 88. 

Charging 

In general, charging shall be started when specific gravity 
of pilot cell is 15 points (.015) less than the last overcharge 
maximum. 

Charging shall be started before this point is reached, if 
necessary, in order that at the close of the day it shall be 
completed, or sufficient to carry the load during the night, 


82 


so that at 8 A.M. the specific gravity of the pilot cell will 
not be lower than 15 points (.015) below the last overcharge 
maximum. 

In offices having only one source of power and a single 
charging unit, charging may be started when the specific 
gravity of the pilot cell is 10 points (.010) less than the 
last overcharge maximum, or at such time as the power plant 
supervisor may direct. 

During charging, the battery charging current shall be 
maintained as near the normal charging rate as possible. 
Where the generator output and load, but not the battery 
charging current can be read on ammeters, the proper bat¬ 
tery charging current shall be maintained by adjusting the 
generator output to the load, plus the normal rate. Where 
the battery charging current can be read on an ammeter, 
it shall be adjusted to the normal rate, care being taken to 
see that the generator output does not exceed the rated 
capacity of the machine. 

Except when overcharging, charging shall be stopped when 
the specific gravity of the pilot cell is 5 points (.005) below 
the last overcharge maximum. For example, if the last 
overcharge maximum was 1.208 charging shall be stopped 
when the specific gravity is 1.203; all readings being cor¬ 
rected to 70° F. 

The temperature of the electrolyte shall be watched while 
charging and if it reaches 105° F., the battery charging 
current shall be reduced or charging temporarily stopped 
until temperature lowers. 

Overcharging 

At regular intervals, the battery shall be charged until 
there is no change in specific gravity of pilot cell during a 
period of four (4) consecutive half hourly corrected readings. 
This specific gravity is known as the overcharge maximum. 

If the battery is charged less than six (6) times per week 
or is disconnected, it shall be overcharged once every two 
weeks. 

If the battery is charged six (6) or more times per week, 
it shall be overcharged once each week. 


83 


Overcharge day shall be designated by the power plant 
supervisor. 

If the battery charging current is less than the normal 
rate, the time covered by four (4) consecutive readings shall 
be extended proportionately. For example, if the current 
is one-half the normal rate, charging shall be continued 
until there is no change in the specific gravity during a 
period of four (4) consecutive hourly readings. 

Care shall be exercised to avoid excessive overcharging 
as this is injurious to the plates. 

Floating 

If there is a possibility of the specific gravity falling during 
the night more than 15 points (.015) below the last over¬ 
charge maximum, the battery shall be floated after the 
charge is completed. All other cases where floating is neces¬ 
sary will be determined by the power plant supervisor. Float¬ 
ing shall not be commenced until fifteen (15) minutes after 
charging is stopped. It is understood that during this inter¬ 
val the charging generators shall be stopped. 

While floating the battery, the generator output shall be 
very carefully regulated to a value approximately equal to 
or slightly less than the load. Allowance shall be made 
for fluctuations in the load, especially when it is dropping, 
so that no current flows into the battery. Charging at a 
low rate, especially when the battery is nearly or fully 
charged, injures the plates and shortens the life of the battery. 

Hydrometers and Thermometers 

Specific gravity readings of the electrolyte shall be taken 
with a standard hydrometer which is correct at 70° F. 
The gravity temperature correction scale (see page 92) 
shall be used to correct readings taken when the temperature 
is above or below 70° F. This correction may be approxi¬ 
mately obtained by adding one point (.001) for each 3° 
above 70° F., and subtracting one point (.001) for each 3° 
below 70° F. For example, if the hydrometer reading is 
1.208 at 76° F., the specific gravity at 70° F. is approximately 


84 


1.210. When a standard storage battery thermometer is 
used, corrections may be read from the scale direct. 

The hydrometer and electrolyte thermometer shall remain 
in the pilot cell when not in use. 

The air thermometer shall be suspended in the battery 
enclosure near the pilot cell but not directly above any cell. 

The hydrometer shall be washed after each overcharge to 
remove the sediment, as this may cause false readings. 


CARE AND MAINTENANCE 


Watering 

To compensate for evaporation and spraying, water shall 
be added to the cells, from time to time, to bring tbe level 
of the electrolyte to height indicated by marker. These 
markers are not interchangeable and are provided by the 
power plant supervisor. Water shall be added in accord¬ 
ance with the following schedule: 

1. Pilot cell. Daily at 8:00 A.M.; using standard rubber 

funnel and tube. 

2. All cells. On overcharge day and at least twice a 

week, immediately after charging is started; also 
at any time there is danger of plates being exposed. 

Water added to cells, other than pilot cell, shall be distrib¬ 
uted over surface of electrolyte. 

Only water approved by the power plant supervisor shall 
be used. Metallic receptacles shall not be used in handling 
water, as any particle of metal would be injurious to the 
battery. 

Voltage 

Readings shall be taken of the total battery voltage daily 
(Sundays and holidays included) at 8 A. M. If this is less 
than 2 volts multiplied by the number of cells in the set, 
the voltage of each cell shall be read. If the voltage of 
any cell is below the minimum (see page 81), charging 
shall be started at once. 


85 


Semi-Annual Battery Discharge 

Semi-annually, at such times and in such central offices 
as the power plant supervisor shall designate, the battery 
shall be discharged until the specific gravity of the pilot 
cell falls 25 points (.025), unless, before that point is reached, 
the voltage of any cell falls to the minimum (see page 81) 
or unless this requires more than 24 hours for a battery 
which is overcharged weekly, or 48 hours if overcharged 
bi-weekly. This discharge shall immediately follow an over¬ 
charge and shall be taken on the day of a Traffic peg count. 

The battery driven ringing, message register, and coin 
collector sets shall be operated during the period of dis¬ 
charge. 

Reports, Daily 

A daily report covering the following items shall be made 
on form provided: 

1. Name of central office, date and day of week. 

2. Time charging started, battery charging current and 

load at that time. 

3. Time charging stopped, battery charging current and 

load at that time. 

4. Time floating started, generator output and load at 

that time. 

5. Generator output and load each half hour during float¬ 

ing period. 

6. Time floating stopped, generator output and load at 

that time. 

7. Voltage of battery at 8 A.M. 

8. Voltage of battery just prior to charging and just before 

charging is stopped. 

NOTE: Special care shall be exercised to maintain 
the battery charging current at the normal 
rate while voltage readings at the end of 
the charge are taken. 

9. Number of cell used as pilot. 

10. Specific gravity of pilot cell every hour during charg¬ 
ing, until the gravity is within two points of end of 


86 


charge and then every half hour. In the case of 
an overcharge, readings shall be taken every hour 
until the specific gravity reaches two points below 
the previous overcharge maximum, and then every 

half hour. 

11. Specific gravity of each cell just prior to charging 

and fifteen (15) minutes after charging is stopped. 

12. Temperature of electrolyte and air before and at end 

of charging. 

13. Special work done, irregularities or trouble. 

14. On days when battery is not charged, voltage of 

battery at 8 A.M. and at 5 P.M., specific gravity of 
pilot cell at 8 A.M. and at 5 P.M. 

Reports, Overcharge 

A copy of report for each overcharge day shall be written 
in ink and forwarded to power plant supervisor. On this 
report shall be noted any special work done, irregularities 
or troubles since preceding overcharge. This report shall 
be approved by Wire Chief and stamped “Overcharge”. 

Reports, Semi-Annual Discharge 

A report of semi-annual discharge covering the following 
points shall be made on blanks provided for that purpose: 

1. Name of central office. 

2. Type and number of plates per cell. 

3. Rated capacity. 

4. Date and time discharge started. 

5. Date and time discharge stopped. 

6. Specific gravity and voltage of each cell at beginning 

and end of discharge. 

7. Half hourly readings of: 

(a) Specific gravity of pilot cell. 

(b) Total load. 

(c) Machine load. 

(d) Total voltage of the battery. 

8. Total incoming calls by hours. 

9. Total originating calls by hours. 


87 


Records 


Daily Report, approved by Wire Chief, shall he filed for 
a period of one year. On the first day of each month the 
oldest month’s record shall be destroyed, leaving a complete 
record for twelve (12) months in the file. The word “Over¬ 
charge” shall be stamped on the report on the day overcharge 
is made. 

Caution 

Because of inflammability of gases from the battery, a 
flame shall not, under any circumstances, be exposed in the 
battery room or battery casing. 

The utmost care shall be exercised to prevent any foreign 
substance from falling into a cell. 

When it is necessary to use metallic tools near the cells, 
great care should be taken to prevent short circuits. In no 
case shall metal tools be used in the cells. 

The tops of battery cases shall be kept clear. No tools 
or apparatus, except accessories used in connection with the 
battery, shall be stored within the battery casings. 

Adjustment of Specific Gravity 

An adjustment of the specific gravity of each cell will be 
made at least once a year by adding electrolyte of 1.400 
specific gravity so that specific gravity at end of overcharge 
will be approximately 1.210. This adjustment is necessary 
to replace loss of acid from the electrolyte, due to gassing 
and absorption by the sediment, and will be made by power 
plant force. 

Under no circumstances shall electrolyte be added to or 
taken from any cell except by direction of power plant super¬ 
visor. 


TWO-PLATE CELLS 

Charging 

Two-plate cells or couples, used for superimposed ringing 
are not operated by the specific gravity method on account 


88 


of the small bulk of the plates and the variation in specific 
gravity of the electrolyte at the different levels. The voltage 
method is preferable. Special charging instructions covering 
each case will be issued by the power plant supervisor. 

Voltage 

The voltage shall be noted twice weekly and action taken 
as per page 85. 

Specific Gravity 

Fifteen minutes after the end of the overcharge, specific 
gravity readings shall be taken of all cells. 

Watering—See (2) Page 85. 

Reports 

A report shall be made only of each overcharge, showing: 

1. Total voltage before and at end of charging. 

2. Specific gravity, as explained above. 

A copy of this report shall be forwarded to the power 
plant supervisor and the original retained in the Wire Chiefs 
files. 


TROUBLES 

Emergency 

A report shall be made of the following conditions: 

1. Any marked variation or difference between specific 

gravity or voltage of any one cell during a compar¬ 
atively short period. 

2. Any changes in color of plates. 

3. Irregularities in gassing. 

4. Corrosion of metal parts. 

5. Failure of electric or gas power service. 

6. Inability to start charging. 

7. Leaky tank. 

8. Low voltage or reversed polarity of any cell. 

9. Any other unusual condition. 


89 


If, from any cause, a cell should become short-circuited or 
completely discharged, charging shall be started at once. 
Cell in which trouble exists shall then be explored with a 
lamp provided for that purpose and trouble remedied. A 
report of trouble shall be made at once to the power plant 
supervisor and if individual charging of cell is necessary, 
instructions to that effect will be given. 

Reversed polarity of a cell occurs only when there are 
several cells in series with each other, and is occasioned 
by complete discharge to zero followed by a charge in the 
reversed direction with a consequent reversal of polarity 
of the plates. This seldom happens except in cases where 
a cell loses its capacity through some accident or defect 
and its discharge is ended before the other cells in series 
with it have been completely discharged. 

If a glass battery jar is cracked so that part of the elec¬ 
trolyte leaks out, temporary repairs shall be made by paint¬ 
ing the crack on inside of jar with asphaltum, beesw^ax, 
paraffine or shellac, and refilling jar with electrolyte or water. 
If a jar is broken so that it cannot be temporarily repaired, 
start the charging set and adjust the generator output to 
carry the exchange load, then remove the electrolyte until 
the plates are almost entirely exposed. The cell may then 
be short-circuited by winding uninsulated copper wire across 
the cell bus bars, after which the remaining electrolyte may 
be drawn off. In case a jar is so broken that the battery 
circuit is opened, service shall be restored at once by cut¬ 
ting in the generator, as described above, after which the cell 
can be short-circuited. It is important that negative plates 
shall be kept wet to prevent injury due to exposure to air. 

Emergency troubles shall be reported orally to the office 
and confirmed in writing. All other troubles shall be re¬ 
ported by memorandum only. 

Short Circuits 

The most frequent trouble is a partial short circuit in a 
cell. This is indicated by: 

1. Absence or deficiency of gassing during overcharge. 

90 


2. Falling off in voltage or specific gravity as compared 

with other cells of the same battery. 

3. Higher temperature than in other cells. 

The cause is usually one of the following: 

1. Lugs touching at top of jar or supporting plates. 

2. A deposit of moss or sediment bridging across the top 

of plates or between the lugs. 

3. Buckled plates. 

4. Sediment touching bottom of plates. 

5. Conducting material between plates. 

Buckled Plates 

This condition may be due to excessive overcharging, 
undercharging or over-discharging. In the first case it is 
due to the excess of peroxide, which takes more room than 
the lead, causing undue expansion in the buttons. In the 
second case it is caused by a deposit of sulphate on or in 
the buttons, clogging them so they cannot expand normally. 
At the first sign of buckling the cause should be determined 
by the indications given above and the condition remedied. 

Impurities in Electrolyte 

This condition is usually indicated by the positive plates 
becoming very light in color and the buttons or active 
material bulging out of the positive plates and becoming 
soft, also by change in color of the electrolyte. 

Poor Connections 

Where the batteries are connected together with bolts, 
the joints should be watched for heating or corrosion. The 
first condition may be noticed by taking hold of the joints 
during overcharge. The second is indicated by a bulge in 
the tape or paint covering the joint. 


91 


120 



. Thermometer with Hydrometer Correction Scale 

(See page 84) 


92 


Fig. 23 































































































PRIMARY BATTERIES 

DEFINITIONS 

Cell 

One complete battery unit. 

Depolarizer 

A chemical compound, which may be either solid or liquid, 
the object of which is to prevent the hydrogen, which is 
liberated by the decomposition of the electrolyte, from ac¬ 
cumulating on the positive pole. 

Electrolyte 

The exciting solution in which one or both of the elements 
are placed. 

Elements 

Those parts which when immersed in a suitable solution 
produce an electric current by chemical action. 

Jar 

A receptacle for holding the electrolyte and the elements. 

Porous Cup 

A cylinder of porous earthenware closed at the bottom 
which is used to keep the electrolyte from mixing with the 
solution in which the zinc is immersed and yet permit an 
electric current to flow from one to the other. 


CHEMICAL ACTION 

In all primary batteries, current is produced by the electro¬ 
lyte attacking the zinc when the circuit is closed, forming 
a salt of that metal and liberating hydrogen. This hydrogen 


93 


tends to collect in minute bubbles on the positive pole and 
increases the internal resistance of the cell. The depolarizer 
is usually composed of some substance rich in oxygen which, 
when the cell is in action, combines with the liberated 
hydrogen and forms water. In all primary batteries the 
carbon or copper is the positive pole and the zinc the 
negative pole. 


DESCRIPTION 

Primary batteries used in central offices are made up 
of three types of cells, namely: 

STANDARD BATTERIES (FULLER TYPE). 

CAUSTIC SODA BATTERIES (LALANDE TYPE). 

DRY BATTERIES. 


STANDARD BATTERY 


Each 

1 . 

2 . 

3 . 

4. 

5. 

6 . 
7. 


cell consists of: 

A glass jar 6" x 8". 

A porous cup. 

A carbon element. 

A zinc element. 

The electrolyte (termed Standard Battery Solution), 
which also acts as a depolarizer. 

A solution of common salt. 

A cover, made of impregnated wood to cover the jar 
and also to act as a support for the carbon element. 


To Set Up Cell « 

1. Thoroughly coat the zinc and its connecting wire with 

mercury, first dipping it into the electrolyte for a 
few seconds. 

2. Place zinc in porous cup with the wire projecting 

above the top of cup. 

3. Place one teaspoonful of mercury in porous cup. 

4. Place porous cup and zinc in glass jar. 

5. Fill porous cup two-thirds full of clean water. 


94 


6. Add one tablespoonful of common salt to water in 

porous cup, dissolving it thoroughly by moving the 
zinc up and down. 

7. Fill glass jar with electrolyte to about i/ 2 " below the 

level of solution in porous cup. 

8. Place cover on jar, passing the wire attached to the 

zinc through the small hole. 

9. Insert carbon in slot in cover. 

When newly set up, this battery has a potential of about 
2.14 volts and the electrolyte has a red color. When ex¬ 
hausted the voltage falls off rapidly and the electrolyte has 
a green color. 

To Renew Cell 

Empty the old electrolyte and salt solution, being careful 
to save the mercury in porous cup as it may be reused in¬ 
definitely. Wash all parts thoroughly and proceed as when 
setting up cell, using new zinc when necessary. After us¬ 
ing a porous cup for three or four renewals it may be found 
that the life of the cell is appreciably shortened. This is 
due to the formation of crystals in the pores of the earthen¬ 
ware which increases the internal resistance of the cell. 
These crystals may be dissolved by immersing the porous 
cup in clean water for from seven to ten days, changing 
the water daily. If crystals form on the carbon they may 
be removed in the same manner. 

CAUSTIC SODA BATTERY 
Each cell consists of: 

1. A jar of enamelled steel or porcelain, or heat resisting 

glass. 

2. A copper oxide element which also acts as a de¬ 

polarizer. 

3. A frame or holder for copper oxide element. 

4. Two zinc elements. 

5. An electrolyte of caustic soda solution. 

6. A layer of heavy paraffine oil to prevent the chemical 

action of the atmosphere on the electrolyte. 

7. A cover which also acts as a support for the elements. 


95 


To Set Up Cell 

1. Fill jar with water such as has been approved for 

storage batteries (avoid water containing iron, lime, 
etc.) to within 1%" of top, disregarding all marks 
or ridges on the jar. 

2. Add gradually one proper sized charge of caustic 

soda, stirring constantly with a stick of wood until 
thoroughly dissolved. Be careful not to slop or 
splash any of the solution on the skin or clothing. 
If it is splashed accidentally, the part should be 
washed IMMEDIATELY, and no harm will result. 
Soda must be added slowly and thoroughly dissolved, 
otherwise it will solidify in bottom of jar. Allow 
solution to cool to at least 90° F. before immersing 
elements. 

NOTE: Never under any circumstances put the soda 
into the jar first and then the water, as 
this procedure is dangerous. 

3. See that rubber tubing insulators are in place on the 

copper frame. Fasten copper oxide plate into po¬ 
sition. 

4. Pass each zinc stem (lettered side out) through the 

square holes in cover, and pass brass bolt through 
the holes in stem and hole in ridge on cover, fas¬ 
tening same in place with wing and jamb nuts. An 
additional wing nut is furnished for connecting the 
conductor. 

5. When properly assembled, the copper oxide plate is 

suspended in the centre of cover with a zinc plate 
on either side. Zincs should hang approximately 
parallel to copper oxide plate and about y 2 " dis¬ 
tant from it. 

5. Immerse elements in electrolyte, noting particularly 
that the rubber insulators on copper frame are 
partly immersed in electrolyte, as otherwise the 
floating particles of copper oxide, which are freed 
when plates are immersed, will short circuit the cell. 
7. Pour the oil on top of electrolyte by moving cover to 
one side, being careful not to allow any of it to 


96 


come in contact with the elements as an insulating 
film may form on new plates which would reduce 
the capacity of the cell. 

To Renew Cell 

The elements and electrolyte are so proportioned that all 
become exhausted at approximately the same time. When 
exhausted, the zincs are worn very thin, the copper oxide 
plate is reduced to metallic copper, and the electrolyte is 
changed from a solution of caustic soda to a solution of 
sodium zincate, and it will be necessary to renew the ele¬ 
ments and electrolyte. 

1. Remove covers with elements attached, empty jar of 

old electrolyte and wash jar, cover and element 
support thoroughly, being careful not to allow the 
solution to come in contact with the skin or cloth¬ 
ing. 

2. Remove old plates from cover and clean channels of 

copper frame with sandpaper or emery. 

3. Make new electrolyte, fasten new elements to cover, 

immerse in electrolyte and apply the oil as directed 
under instructions “To Set Up Cell”. 

New Type Cell 

The above instructions refer to the older types of caustic 
soda cells. A newer type has been developed in which the 
elements are assembled complete at the factory. When 
necessary to renew the newer type cell, the old elements 
are removed as a unit by unscrewing the clamping nuts on 
cover and a new complete element placed in its stead. 
Otherwise the same instructions will apply. 

DRY BATTERY 
Each cell consists of: 

1. A jar or container of zinc which also serves as the 

negative pole. 

2. A carbon element. 


97 


3. A powdery depolarizer consisting of manganese per¬ 

oxide, or its equivalent, which surrounds the carbon 
element. 

4. An absorbent lining which, with the depolarizer, is 

saturated with electrolyte. 

Renewals 

Dry cells are so constructed that the depolarizer is de¬ 
pleted and the zinc container used up at about the same 
time. When the cell is exhausted it is discarded in its 
entirety and a new cell substituted. 


USES 

In Central Offices, primary batteries are used to 
supply current for the following purposes: 

STANDARD BATTERY 

Voltmeter testing combination with low resistance shunt. 
CAUSTIC SODA BATTERY 

Operating the vibrating arm on pole changers in local bat¬ 
tery central offices. 

DRY BATTERY 

1. Operating coin collectors. 

2. Ringing with pole changers. 

3. Silent period. 

4. Superimposed ringing. 

5. Testing circuits. 

6. Circuit trunk booster batteries, etc. 

7. Operators’ transmitters in local battery central offices. 

8. P.B.X. emergency batteries. 

9. Operating bells and other signals in local battery cen¬ 

tral offices, or where it would not be advisable to use 
central office storage battery for this class of service. 


98 


TESTS 


STANDARD BATTERY 

As this battery is used for testing, its condition should 
be noted when making regular tests. 

CAUSTIC SODA BATTERY 

This battery is designed so that the copper oxide plate and 
electrolyte become depleted at the same time that the zincs 
are consumed and, as the voltage remains unchanged as long 
as any copper oxide remains, no test is necessary, but 
periodic inspections should be made towards the end of the 
life of the battery by lifting the elements and observing the 
condition of the zinc. 

DRY BATTERY 
Coin Collector Battery 

This consists of four sets of cells, each set comprising 
eighty cells with a maximum of 120 volts open circuit. Bat¬ 
teries shall be tested each morning in order to detect de¬ 
fective cells. 

Test shall be made by bridging a voltmeter shunted by a 
500-ohm resistance across each set. If voltmeter reading 
shows 110 volts or over at the end of 10 seconds, the set 
under test shall be considered good. If voltmeter reading 
shows less than 110 volts each cell shall be tested individu¬ 
ally as described under “Individual Cell Tests” and defective 
cells replaced. 

In addition to the daily test a weekly test shall be made 
of each cell as described under “Individual Cell Tests” and 
all defective cells replaced. 

Main Ringing Battery 

This is comprised of from 66 to 80 cells with an open 
circuit maximum of 100 volts. Batteries shall be tested each 
week in order to detect defective cells. 


99 


Test shall be made by bridging a voltmeter shunted by a 
500-ohm resistance across the set. If voltmeter reading 
shows 80 volts or over at the end of 10 seconds, the set 
under test shall be considered good. If voltmeter reading 
shows less than 80 volts, the cells shall be tested individu¬ 
ally as described under “Individual Cell Tests” and defec¬ 
tive cells replaced. If the individual cells test good a suffi¬ 
cient number of new cells shall be added to bring the open 
circuit voltage up to 100. 

Superimposed Ringing Battery 

This is used in connection with pole changers or hand 
generators and consists of two sets, one for positive and 
one for negative superimposing. Each set comprises from 
42 to 50 cells with a maximum of 65 volts open circuit. 
Batteries shall be tested each week in order to detect de¬ 
fective cells. Test shall be made by bridging a voltmeter 
shunted by a 500-ohm resistance across the set. If volt¬ 
meter reading shows 55 volts or over at the end of 10 
seconds, the set under test shall be considered good. If 
voltmeter reading shows less than 55 volts, the cells shall 
be tested individually as described under “Individual Cell 
Tests” and defective cells replaced. If the individual cells 
test good a sufficient number of new cells shall be added 
to bring the open circuit voltage up to 65. The emergency 
superimposed battery shall be cut into service when tests 
or replacements are being made. 

Superimposed Bell Adjusting Battery 

This is used in connection with Wire Chief’s low voltage 
ringing test and consists of two sets, one for negative and 
one for positive superimposing. Cells shall be tested weekly 
as described under “Individual Cell Tests” and defective 
cells replaced. The number of cells varies for different 
offices, and is shown on the bell adjusting circuit drawing. 

Voltmeter Testing Battery 

The number of cells varies for different offices and is 
shown on the testing circuit drawings. Test shall be made 


100 


daily by short circuiting a test plug. If set shows one volt 
or more below the standard, the voltage shall be corrected 
by adding a new cell or replacing defective cells. 

Booster Batteries 

These are used in connection with incoming trunks, silent 
period, etc., to increase the working voltage. The cells vary 
in number with the increase in voltage desired. Tests shall 
be made weekly as described under “Individual Cell Tests” 
and defective cells replaced. 

Operators’ Transmitter Battery 

This is used in local battery exchanges for operators 
telephone sets. Battery shall be tested each week as de¬ 
scribed under “Individual Cell Tests” and defective cells 
replaced. 

P.B.X. Emergency Battery 

This consists of sixteen cells. Battery shall be tested 
each week in order to detect defective cells. Test shall 
be made by bridging a voltmeter shunted by a 100-ohm re¬ 
sistance across the set. If voltmeter reading shows 20 
volts or more at the end of 10 seconds, the set shall be 
considered good. If voltmeter reading shows less than 20 
volts, each cell shall be tested individually as described 
under “Individual Cell Tests” and defective cells replaced. 

Batteries for Miscellaneous Purposes 

When maintained by the Plant Department, cells shall be 
tested each week individually as described under “Individual 
Cell Tests” and defective cells replaced. 

Individual Cell Tests 

A. Standard Battery Gauge W. E. Co. #35. 

With Stem Depressed 

If the reading remains at or above the second red mark 
for a period of one minute, the cell under test shall be con¬ 
sidered good for 

P.B.X. Emergency and Talking Batteries. 

101 


If the reading remains at or above the black mark for 
a period of 5 seconds, the cell under test shall be considered 
good for all other batteries than the above. 

If the reading is below the black mark, the cell shall be 
discarded. 

B. Eldridge Gauge. 

If the reading is at or above the higher calibration mark 
after 10 seconds, the cell under test shall be considered 
good for 

1. Coin Collector Battery. 

2. P.B.X. Emergency and Talking Batteries. 

If the reading is at or above the lower calibration mark 
after 10 seconds, the cell under test shall be considered 
good for all other batteries than the above. 

If the reading is below the lower calibration mark, the 
cell shall be discarded. 

Reserve Batteries 

When batteries for similar services are furnished in 
duplicate, the central office load shall be transferred three 
times daily—at 10 A.M., 2 P.M. and 5 P.M. Additional 
transfers shall be made at night if conditions require. 


102 




POLE CHANGERS 

No. 84 Type Interrupter 
DEFINITIONS 


Magnet Springs 

A pair of contact springs mounted on the vibrator arm sup¬ 
port, and connected in the circuit of the operating magnet and 
battery. The motion of the vibrator arm serves to alternately 
open and close the contact and thus maintain the arm in 
motion. 


Operating Battery 

A battery for operating the vibrator arm. 


Operating Battery Reversing Key 

A key connected in the circuit of the operating battery to 
reverse the polarity of the battery at the magnet spring con¬ 
tacts. This reverses the deposit of metal from one contact 
to the other, which takes place in the direction of current 

flow. 


Operating Key 

A small key mounted in the base of the pole changer and 
connected in the circuit of the operating and ringing batteries. 
This key is used for starting and stopping the pole changer 
when a separate key or switch is not provided. 


Operating Magnet 

An electro magnet connected to the operating battery to 
keep the vibrator arm in motion. 


103 


Pole Changer 

An electrically operated vibrating device, by means of which 
the direct current furnished by a battery may be rapidly re¬ 
versed in direction, or interrupted, to produce an alternating 
or pulsating current. 

Ringing Battery 

A battery of dry cells connected to the ringing springs to 
furnish alternating and pulsating ringing current. 

Ringing Springs 

Four pairs of stationary contact springs connected to the 
ringing battery and to the positive pulsating and negative 
pulsating binding posts. When the vibrator arm is in motion, 
the contacts of the ringing springs engage the contact points 
mounted on the swinging end of the arm. 

Vibrator Arm 

A swinging arm suspended between pivots and arranged to 
be kept in motion by an electro-magnet. The swinging end 
of the arm is equipped with contact points, which alternately 
make contact with the positive and negative ringing springs. 


Vibrator Arm Set-Nuts 

A pair of knurled thumb-nuts located on the swinging end 
of the vibrator arm and used for adjusting its speed. 

Vibrator Arm Spring 

A spiral spring attached to and used for adjusting the speed 
of the vibrator arm and the ringing current voltages. 


104 


DESCRIPTION 


Four styles of the it 84-type interrupter are in use. These 
differ only in the winding of the operating magnet and are 
as follows:— 


Type of No. of Oper- 

Interrupter ating Cells Voltage 


Type of Oper¬ 
ating Battery 


8 4-A 

11 

84-B 

2 

84-C 

17 

84-E 

1 


20-28 Storage 

1.4 (Approx.) Lalande 

31-43 Storage 

.7 (Approx.) Lalande 


All styles of the # 84-type interrupter are wired in the 
same manner. 

In common battery offices a #5-AA retardation coil is con¬ 
nected in the ringing ground lead to prevent noise on the 
battery. 


OPERATION 

The key used for starting the pole changer may be the 
operating key provided in the base of the instrument, a switch 
located on the power switchboard, or a key installed on the 
face of the switchboard. 

When a separate operating key or switch is provided, the 
operating key in the base of the pole changer should always 
be left in its “ON” position, except when adjusting or testing 
the instrument. 

To Start 

Close the operating key or switch. 

NOTE: If pole changer does not start promptly restore 
the operating key or switch and inspect for 
trouble as described later. Do not attempt to 
start the pole changer by jarring or by 
swinging the vibrator arm with the hand. 


105 


To Stop 

Restore the operating key or open the switch. 

To Transfer Load from one Pole Changer to Another: 

1. Start pole changer to be cut into service. 

2. Throw transfer switches. 

3. Test ringing. 

4. Stop pole changer to be cut out of service. 


RESERVE SETS 

When emergency superimposed current batteries are pro¬ 
vided for use with either pole changer, they shall be used one 
day each week. 

Where two pole changers are provided, they shall be oper¬ 
ated on alternate days. 

Where three pole changers are provided, they shall be oper¬ 
ated regularly as follows: 

First Second 

Half of Half of 

Switchboard Switchboard 

1st Day P.C. #1 P.C. #2 

2nd Day P.C. #2 P.C. #3 

3rd Day P.C. #3 P.C. #1 

4th Day Same as 1st day, etc. 

Where the exchange load is not great enough to require 
the use of two pole changers during the day, each pole changer 
shall be operated on the entire switchboard every third day. 


Entire 

Switchboard 

1st Night P.C. #2 

2nd Night P.C. #3 

3rd Night P.C. #1 


TROUBLES 

Stopping or Failure to Start may be due to: 

1. Low voltage of primary operating battery. 

2. Open operating battery circuit. 


106 


3. Poor contacts on magnet springs. 

4. Improper adjustment of magnet springs. 

5. Improper adjustment of spiral spring. 

6. Location of vibrator, arm too near operating magnet. 

7. Worn or loose pivot screws. 

Sparking at Contacts may be due to: 

1. Rough contact points. 

2. Contact springs out of adjustment. 

3. Open condenser circuit. 

4. Open non-inductive resistance circuit. 

5. Ground on ringing leads. 

Noisy Operation may be due to: 

1. Vibrator arm striking operating magnet. 

2. Worn or loose pivot screws. 

Loss of Ringing Current may be due to: 

1. Open battery fuses. 

2. Open connections of dry cells. 

3. Defective dry cells. 

4. Grounded ringing leads. 

5. Springs out of adjustment. 

6. Short or open circuit in pole changer. 


CARE AND MAINTENANCE 

Adjustment of Ringing Springs 

The vibrator arm and operating magnet are so placed that 
the ringing springs have a considerable margin of adjustment. 
The ringing springs should not be readjusted unless a careful 
inspection has first shown them to be out of adjustment. Re¬ 
move the ringing battery fuses before adjusting the springs. 

When the vibrator arm is held in the middle of its swing, 
the distance between the contacts on the arm and the inner 
ringing springs (see page 112) should not be less than .01 inch 
or more than .015 inch. If the distance is less than .01 inch 
on a side, there is a possibility of a short circuit between the 

107 


two springs. If the distance is greater than .015 inch, the 
ringing voltage will be low. With proper adjustment the 
voltage of the alternating current should be about 80 per 
cent, of the voltage of the ringing battery. 

The distance between the contacts of the outer and inner 
ringing springs, “A” and “C” and “A” and “F” (see page 112), 
may be less than the distance between the contacts of the 
vibrator arm and inner springs, since both springs are of the 
same polarity. In most cases, a break distance .01 inch will 
be found satisfactory. If this distance is exceeded the pul¬ 
sating voltage will be low. 

The above distances should be measured by means of the 
gauges accompanying each instrument. 

In making adjustments as above, it should be borne in mind 
that when swinging in either direction, the alternating and 
ground contacts of the vibrator arm should make contact at 
the same instant with their ringing springs; also that when 
the vibrator arm forces the inner springs against the outer 
springs, the contacts of the two sets of springs must make 
at the same instant. 

The springs should have a slight tension in the direction of 
their stop springs and lie flat against them for their entire 
length. In case it becomes necessary to adjust the ringing 
springs, their stop springs should, if necessary, be adjusted 
also, to keep the same relative position; that is, the ringing 
springs should remain lying flat against their stop springs, 
as described above. If, in order to properly adjust the ringing 
springs, considerable movement of these springs is necessary, 
the entire group of springs should be moved by loosening the 
screws which fasten these springs to the post, after which a 
complete readjustment and spacing of the springs of the 
interrupter will be necessary. 

When the vibrator arm is in motion, the ringing springs 
“A” should not strike the stop springs of the outside ringing 
springs “C” and “F.” (See page 112) 

Adjustment of Magnet Springs 

The inner magnet spring “D” (see page 112) should have 
sufficient tension on the bumper pin to cause it to follow the 


108 


vibrator arm through its entire stroke. The outer magnet 
spring “E” (see page 112) should have sufficient tension in the 
direction of its adjusting screw “S” (see page 112) to cause it 
to lie flat against its stop spring and also sufficient tension in 
the direction of the inner magnet spring to cause it to follow 
the latter nearly to the point where the alternating and 
ground contact points make contact with the ringing springs. 
Care should be observed in making this adjustment to 
insure the opening of the contact at the proper time in 
order not to consume an undue amount of power, and yet pro¬ 
vide a strong enough swing. 

The bumper pin underneath the inner magnet spring is 
made of hard rubber and very carefully polished. After being 
in service for some time this pin is liable to become rough¬ 
ened. It should be polished occasionally with crocus cloth, 
as the wear is very materially increased if allowed to go on 
after it has become roughened. 

Adjustment of Vibrator Arm Spring 

The best regulation of the vibrator arm when the operating 
voltage varies is obtained when the tension in the spiral 
spring is light. Care should therefore be taken to avoid in¬ 
creasing the tension more than is necessary. The tension 
should be sufficient to close the magnet spring contacts when 
the vibrator arm is at rest, insure the proper positive pulsating 
voltage and prevent the vibrator arm locking over against the 
operating magnet when the starting switch is closed. 

Care of Contacts 

If contacts become rough, they shall be polished with crocus 
cloth. 

Speed Regulation 

The rate of vibration of the vibrator arm should be about 
1,000 per minute. 

The vibrator arm speed may be increased by moving the 
vibrator arm set-nuts nearer the operating magnet and de¬ 
creased by moving them further away from the magnet. The 


109 




proper location of these nuts, when the other adjustments are 
properly made, is in the center of the threaded portion of- 
the vibrator arm. 

The speed of the vibrator arm is also affected by the tension 
of the spiral spring and the adjustment of the magnet spring 
contacts. 

It is important that the tension of the spiral spring be not 
too heavy, nor the vibrator arm too near the operating magnet. 

The interrupter speed can be satisfactorily adjusted by the 
use of a set of biased test bells. When two interrupters are 
provided, their speeds may be compared and adjusted by ring¬ 
ing the test bells alternately from either interrupter. When 
but one interrupter is provided, its speed may be adjusted by 
ringing the test bells first with the hand generator and then 
with the interrupter. 

Voltage Regulation 


With the ringing springs and vibrator arm properly adjusted, 
the comparative voltages at the binding posts of the pole 
changer should be as follows: 




Pulsating 

Voltage 

Voltage of 

Alternating 

(wRiTaxT. 

(with D.C. 

Ringing Battery 

Voltage 

Voltmeter) 

Voltmeter) 

80 

67 

49 

32 

85 

71 

52 

34 

90 

75 

55 

36 

95 

79 

58 

38 

100 

83 

61 

40 


Increasing the tension of the spiral spring raises the posi¬ 
tive pulsating voltage, while tightening the screw of the 
outer magnet spring “S” (see page 112) raises the negative 
pulsating voltage. The alternating voltage also is affected by 
these adjustments, being raised when the adjustments of the 
spiral spring and magnet spring contact increases the swing 
of the vibrator arm, and lowered when their adjustment de¬ 
creases the swing. 

When regulating the voltage, readings should in all cases 
be taken of the positive and negative pulsating voltages and 

no 


these voltages made to correspond. In offices where pul¬ 
sating ringing current is not used, this is necessary in order 
to insure an alternating current made up of equal positive and 
negative impulses. 

No attempt shall be made to increase the ringing voltages 
by adjusting the pole changer without first measuring the 
voltage of the ringing battery, as provided in Section on 
“Primary Batteries”, to determine that its voltage is within the 
limits shown on the ringing circuit drawing for the particu¬ 
lar office. 

Battery Maintenance 

The operating, ringing, and superimposed current batteries 
used with pole changers shall be maintained in accordance 
with the instructions in section on “Primary Batteries”. 

Inspections 

In offices covered regularly by a plant man, the pole chang¬ 
ers shall be inspected weekly for the following: 

1. Failure to start promptly when operating key is closed. 

2. Sparking at contacts of ringing or magnet springs. 

3. Noisy operation. 

4. Tendency of vibrator arm to stick against magnets. 

5. Speed of vibrator arm. 

6. Voltage at operating battery binding posts (when pri¬ 

mary battery is used). 

7. Voltages at alternating and pulsating current binding 

posts. 

8. Condition of contacts. 

In offices not regularly covered by a plant man, inspections 
shall be made weekly if possible. When this is not practi- 
cable, inspections shall be made whenever a plant man visits 
the office. 

Reversing Key 

The operating battery shall be reversed weekly by means 
of the reversing key. 


Ill 



Fig. 24. #84 Type Interrupter. 

(See pages 107, 108, 109 and 110) 


112 


OPERATING KEY 



























































































































Fig. 25. Pole Changer—Pulsating Ringing 


113 

































Fig. 26. Pole Changer—Superimposed Ringing. 


114 


Superimposed Ringing Battery 










































MISCELLANEOUS POWER AND LIGHT¬ 
ING APPARATUS 


FUSES 

DEFINITIONS 

Fuse 

A protective device consisting of two terminals between 
which is connected a section of alloy which melts when the 
current flow exceeds a predetermined amount and thus opens 
the circuit. 

Fuse Wire 

A wire made of alloy which melts at a predetermined tem¬ 
perature. 

NOTE: Fuse wire shall not be used without Wire Chiefs 
permission, except as noted under “Power 
Fuses”. 

Link Fuse 

A fuse having the alloy exposed and soldered to terminals. 

Mica Fuse, #24-Type 

A fuse having the terminals and alloy supported on a strip 
of mica. 

NOTE: Mica fuses are made only in small capacities. 

Mica Fuse, #35-Type 

A mica fuse equipped with a mechanically indicating device 
and so arranged that when the fuse operates, audible and 
visible signals are automatically given. 

Non-Arcing Fuse 

A fuse having the alloy enclosed in a fibre sleeve provided 
with a device to indicate when the fuse has operated. 


115 


CARE AND MAINTENANCE 


General 

Any employee who is directly responsible for placing in 
service fuses of unauthorized capacity, or any employe who 
detects unauthorized fuses in service and who fails to notify 
Wire Chief or Foreman, or any employe whose duty it is to 
inspect this apparatus and who fails to make such inspections 
or to detect the existence of unauthorized fuses, shall be liable 
to dismissal. 

Special attention shall be given to the inspection of fuses 
while outside forces are working in the building. 

A sufficient number of spare fuses of the various types and 
sizes used in the central office, and a spool of 1-ampere fuse 
wire shall be kept on hand at all times. 

In buildings where no licensed engineer is stationed, a 
stock of electric light and power service fuses shall also be 
carried by the Wire Chief. 

Fuse drawers with compartments marked to indicate the 
type and capacity of fuses contained therein shall be provided 
and mounted at convenient points in the terminal room. 

Tools for replacing fuses shall be kept near the power board, 
and an inspection shall be made at 8:00 A.M. and 5:00 P.M. 
to insure their being in proper place. The ampere capacity 
of the proper link or non-arcing fuse to be used shall be 
marked in each case near the fuse studs. 

When fuses are placed in service, the contact surfaces of 
fuse terminals and fuse studs shall be thoroughly cleaned. 
Screws holding fuses in place shall be tightened with a wrench 
or screw-driver, but care shall be exercised to prevent damag¬ 
ing the heads of screws, twisting lugs or injuring fuses. 
Where two or more fuses are placed in multiple, special care 
shall be taken to keep the contact resistances at a minimum, 
so that each fuse will carry its share of current. Uneven 
distribution of current reduces the total capacity of fuses in 
multiple. 

Power fuses shall be inspected weekly for proper capacity, 
excessive heating and general condition. 


116 


Battery Discharge Fuses 

In case a fuse equipped with a short circuiting device should 
operate, the short circuiting device shall be closed before at¬ 
tempting to replace the fuse. After the new fuse has been 
placed, it shall be ascertained by observation of the discharge 
ammeter that the load is below the carrying capacity of fuse 
before the short circuiting device is opened. In case a fuse 
not so equipped should operate, the circuit shall first be closed 
with a heavy screw-driver or other suitable piece of metal. 
The metal shall be held firmly against the fuse studs to avoid 
opening the circuit after it has been established, as the re¬ 
sulting arc would quickly heat or burn the metal. 

Mica Fuses 

When a main fuse operates, it generally happens that when 
the circuit is restored, a large number of mica fuses also 
operate, due to the excessive load. When this condition oc¬ 
curs, the retaining screws shall be loosened and 1-ampere 
fuse wire shall be temporarily wound, in zig-zag fashion, be¬ 
tween the retaining screws on the bus bar and those on the 
fuse studs, in order to restore service as quickly as possible; 
after -which the old mica fuses shall be individually replaced 
with new mica fuses and the fuse wire shall be removed. 

When replacing mica fuses, the retaining screws shall be 
loosened sufficiently to allow the fuse to be slipped into place 
without force. If necessary, the screw shall be entirely re¬ 
moved from the bus bar or stud. Care shall be exercised to 
avoid damaging the fuse. Fuses shall be placed with the fuse 
wire toward the outside. 

In replacing mica fuses of the #35-type, inspect the flat 
feather spring on the underside of fuse and see that the end 
is midway between the two rivets which fasten the metal 
terminal to the mica base. If the spring is found to be bent, 
the fuse should be discarded. Fuses shall be inserted so that 
the terminal carrying the feather spring shall be connected 
to the bus bar. After the fuse is secured in place, inspect 
fuse by sighting through the fuse wire hole in the mica base. 
If the alarm spring is not properly centered, the fuse shall 


117 


be removed. The fuse shall also be inspected to see that the 
end of the brass wire carrying the indicator bead is not in 
contact with the metal bus bar terminal. 

When, for any reason, a large number of adjacent mica 
fuses operate, service may be restored temporarily by means 
of fuse wire as described above. After replacing a mica fuse, 
make entry in fuse book, showing circuit and fuse number, 
time and initials of the party making the replacement. 

Mica fuses shall be inspected monthly for the following 
irregularities: 

1. Improper type. 

2. Unauthorized capacity. 

3. Broken micas. 

4. Loose connections. 

5. Crosses. 

6. Wrongly placed fuses. 

7. More than one fuse per stud. 

All irregularities shall be corrected at once and Wire 
Chief notified. 

Electric Light and Power Fuses 

Fuses located in transformer vaults shall be replaced by 
Light or Power Company employes only. Fuses, other than 
those located in transformer vaults, may be replaced by the 
Wire Chief or engineer. Extreme care shall be exercised 
to prevent accident, either to person or property, while at¬ 
tempting to replace fuses. No fuse shall be replaced until 
the load has been removed from the circuit. 

In case a service fuse should operate, in connection with 
duplicate service, the duplicate service switch shall be thrown 
to the other source of supply. After the fuse has been re¬ 
placed, the switch shall be thrown back to its original position. 

The use of 10-ampere link fuses for circuits designed to 
carry 660-watts is allowable, but it is desirable that link 
fuses of 6-ampere capacity, or less, be used on such circuits 
wherever practicable. Wall and ceiling electric light outlets 
will be fused only at the panel box, in accordance with 
Underwriters’ requirements. 


118 


SWITCHES 

DEFINITION 

Switches are devices used to open or close electric circuits. 
All switches mounted on the power boards are designated 
to indicate the circuit which they control. 

CARE AND MAINTENANCE 

The contact surfaces of switch blades and jaws shall be 
kept clean and smooth, and the bolts securing the cross-bars 
and handles shall be kept tight. When insulating fibre stops 
are provided, they shall be kept in place in the switch jaws 
at all times when the switches are not closed. 

AMMETERS AND VOLTMETERS 

CARE AND MAINTENANCE 

Under no circumstances shall instrument seals be broken 
or ammeter shunt leads repaired by the central office force. 

Any defects shall be immediately reported to the power 
plant supervisor. 


RESISTANCE LAMPS 

DESCRIPTION 

Resistance lamps are used as protective devices and are 
wired in series with the source of current supply, the object 
being to limit the amount of current flow under the most 
severe condition. Resistance lamps are placed in all coin 
collector battery feeders and in the majority of ringing gen¬ 
erator feeders. 

INSPECTION 

The resistance lamps and sockets used in connection with 
the above circuits shall be inspected quarterly for proper 
resistance and socket defects. This inspection shall be made 
during the months of February, May, August and November. 
Defects discovered shall be remedied at once and a report 
made to the Wire Chief. 


119 


ALARMS 

Audible alarms are provided in connection with sources of 
battery, message register and ringing generator supply, and 
when operated indicate an abnormal condition or a total fail¬ 
ure of supply. 

Alarms are divided into two classes, namely: 

FUSE ALARMS. 

MACHINE ALARMS. 

FUSE ALARMS 

Audible and visible signals are provided in connection 
with fuses to indicate when the fuse operates. These alarms 
are provided in connection with message register feeders, 
coin collector feeders, private branch exchange feeders, line 
relay, line lamp and other important central office feeder 
circuits. 

OPERATION 

1. Where # 24-type fuses are used in connection with 

message register, private branch exchange, line re¬ 
lay, line lamp and other important central office 
battery feeders, a # 51-type drop is bridged across 
the fuse terminals. When fuse operates and the 
circuit is closed, current flows through the winding 
and energizes the drop. This releases the shutter, 
which closes a local bell circuit. The bus bar and 
fuse number are painted on the face of the drop to 
indicate the fuse that has operated. (See page 128) 

2. Where # 24-type fuses are used in connection with 

central office fire drill bell, a # 51-type drop is 
bridged across the fuse terminals. To the outside 
fuse terminal is connected a 1200-ohm resistance to 
ground. When fuse operates, battery flows through 
the drop and resistance to ground, and the drop 
shutter is released, which closes the local bell cir¬ 
cuit. (See page 129) 

3. Where #35-type fuses are used in connection with 

message register, private branch exchange, line 
relay, line lamp and other important central office 

120 


battery feeders, a special bus bar is placed between 
the fuse studs and battery bus bar. When fuse 
operates, the feather spring, located on underside 
of fuse, is released and makes contact with the 
alarm bus bar, which closes the circuit through a 
pilot lamp and relay to ground. The operation of 
this relay closes the alarm bell circuit. The pilot 
lamp indicates the bus bar and the raised bead indi¬ 
cates the fuse. (See page 130) 

4. Where #35-type fuses are used in connection with 
coin collector battery feeders, the circuit and oper¬ 
ation are the same as (3) except that the pilot lamp 
is omitted. 

CARE AND MAINTENANCE 

All fuse alarm drops used in connection with #24 fuses 
shall be tested annually during the month of June in the 
following manner: 

Remove the fuse in the lead that is common to each group 
of drops. Touch the fuse stud with the end of a wire, the 
other end of which is connected to ground through a 1 y 3 
ampere fuse. The ground fuse should operate the instant 
the ground wire touches the common wire stud. At the 
same instant all drops in good working condition should 
operate. Drops that fail to operate shall be tested separately. 
All drops shall be inspected for shutters that stick and for 
other defects. The local circuit, bell or buzzer, shall be 
tested by operating each shutter manually. 

In central offices where one fuse is common to more than 
one group of drops, test shall be made by removing the 
common wire and applying the ground wire at that point. 
All strap connections shall be inspected. 

MACHINE ALARMS 
Message Register Generator Alarm 

An alarm is provided in connection with message register 
generators to indicate a variation of three volts above or 
below the required e.m.f., which is normal at 39 volts. 


121 


OPERATION 


This alarm consists of a Weston Electrical Instrument 
Company’s model #30 relays equipped with iridium ball 
contacts and a #122-CT relay wired in connection with the 
contacts of the #30 relay. These contacts are so adjusted that 
if the e.m.f. variation is greater than 6 volts, the #122-CT 
relay is operated, which in turn operates the alarm bell. 
(See page 131) 

When the alarm operates and the generator is still running, 
with no indication of contact trouble, adjust the voltage to 
the proper point by manipulating the generator field rheostat. 
If the generator has stopped, start the reserve set as pro¬ 
vided in section on “Motors and Generators”. 

Rifiging Generator Alarm 

An alarm is provided in connection with ringing generators 
to indicate low voltage. 


OPERATION 

The alarm consists of a #85-type relay with three 2 M.F. 
condensers wired in series and bridged across the ringing 
current bus bars at fuse panel. The apparatus is mounted 
in the rear of power board. 

When generator voltage drops, the relay is released and 
closes a local contact, which completes the circuit through 
a direct current vibrating bell operated by storage battery 
current. A 37-ohm resistance and condenser are bridged 
across the contacts of the bell to reduce the sparking at 
that point. The bell rings continuously until the ringing 
current is restored. 

The alarm shall be observed for operation whenever the 
central office load is transferred from one machine to another. 
The alarm shall also be tested once a month. This test 
shall be made by removing the fuse from the lead supplying 
the ringing current to the #85-type relay and observing the 
operation of alarm and bells connected to the circuit. (See 
page 132) 


122 


ELECTRIC FANS 


Electric fans are provided in operating and terminal rooms 
in order to improve the ventilation. 

CARE AND MAINTENANCE 

Fans will be dusted daily by the Real Estate force, other¬ 
wise the maintenance devolves upon the Wire Chiefs force. 

INSPECTION 

During the season when operated, electric fans shall be 
inspected daily (prior to 10:00 A.M. unless otherwise speci¬ 
fied) for the following: 

1. Oil leaks. 

2. Heating or improper operation. 

3. Pendant cord not securely fastened by means of sewing 

twine to lower portion of fan guard. 

4. Pendant switch not in danger of making contact with 

fan guard or being pulled through back of guard by 

fan blades. 

During the entire year fans shall be inspected monthly to 
see that: 

1. Commutators, brushes, blades, guards, and leads are 

in good condition. 

2. Lubricating cups are filled and operate properly. 

3. Ceiling fans are secure. 

4. Fans operate properly. 


ELECTRIC LIGHT AND POWER CIRCUITS 

OPERATION 

Wiring 

Under no circumstances shall any changes be made in 
wiring on central office premises unless authorized by the 
Ofiice. All requests for changes in wiring shall be forwarded 
to the office by the Wire Chief. 


123 


Failure of Current Supply 

Whenever the light or power current supply fails, the Wire 
Chief shall immediately take the necessary steps to restore 
telephone service to normal, notify the Light or Power 
Company of the failure and report condition to the office. 

Duplicate Electric Service Feeds 

All members of the force whose duties require them to 
•operate any part of the power plant, shall familiarize them¬ 
selves with location and operation of switches in connection 
with this service. Before operating these switches, battery 
driven sets shall temporarily be placed in service. 

In general, where light and power circuits are wired to 
separate switches, the power switch should be connected to 
one source of supply and the lighting switch to the other. 

Fuses—See Page 118. 

Polarity of Hubbell Receptacles 

1. In new offices and offices not equipped with Hubbell 

receptacles, any receptacles which are installed will 
be of the polarity type. This type is similar to the 
ordinary Hubbell receptacle except that the contacts 
are at right angles to each other, thereby insuring 
the proper insertion of the plug. All polarity type 
receptacles shall be installed so as to have ground 
side of the circuit, if any, connected to the horizontal 
contact of the receptacle. This contact should be 
uppermost if the receptacle is so placed that one 
contact is above the other and to the right when the 
receptacle is placed with the contacts side by side. 

2. In buildings which are now partly or wholly equipped 

with the original type Hubbell receptacle, the use 
of this type will be continued for any additions or 
replacements. The polarity of these receptacles and 
associated plugs shall be indicated as follows: 

(a) Receptacle. The face plates used in connection 
with these receptacles are held in place by 
two wood screws. Where these screws are 


124 


vertical, lower screw shall be provided with 
an additional slot at right angles to regular 
slot, thus forming a mark. If screws 

are in a horizontal position, screw having the 
extra slot shall be placed to the left. 

After the screw is inserted, the slot shall 

be filled with black lead or some similar sub¬ 
stance, in order to facilitate the detection of 
any change. 

(b) Plug. One prong of plug shall be stamped with 

a mark. It shall be noted in “a” and 

“b” that the mark is used only to desig¬ 
nate the live or non-grounded side of circuit 
and does not necessarily designate positive 
side of circuit. 

Wire Chiefs will be responsible for proper 
marking of all present and future installations 
of this apparatus. 

In offices using non-grounded lighting circuits, 
designations such as the above will be un¬ 
necessary. 

(c) Lamp Socket. Extension cords shall be made 

up so that exposed metal parts of lamp socket 
shall not be connected to marked prong of 
plug. 

Drop Light Cords 

Electric light cords in terminal rooms shall, when replaced, 
be left extra long in order to avoid unnecessary changing 
of cords when making repairs. Portable or drop electric 
light cords which are known to be defective in any way, or 
the appearance of which suggests improper condition, shall 
not be used but shall be repaired or their condition immedi¬ 
ately reported. If, while using portable electric light cords, 
it becomes necessary to leave vicinity of work, the cord shall 
be disconnected from the lighting circuit. 

One emergency lamp cord, properly tagged, shall be kept 
in an accessible place in each operating and terminal room. 
Metal guards or reflectors shall not be used on drop or 


125 


portable light cords in the vicinity of storage batteries, power 
boards, fuse panels or machines, without special permission. 
Cords used at the above points shall be equipped with in¬ 
sulated lamp sockets of the keyless type. 

ROUTINE INSPECTIONS 
Extension Cord Outlets 

Shall be inspected and tested weekly by connecting a lamp 
to each socket. Twin plug outlets or Hubbell receptacles, 
used on grounded lighting circuits, shall be inspected for 
polarity. Troubles found shall be remedied and a report 
made to Wire Chief. 

Drop, Portable and Emergency Lamp Cords 

Shall be tested weekly for cut-outs and other defects by 
lighting lamp, shaking cords, and operating socket keys. 

Protector handles, cords, lamp sockets, guards and ceiling 
outlets shall be inspected. 

Twin or Hubbell plugs on portable or emergency lamp 
cords used on grounded lighting circuits shall be inspected 
for polarity. Troubles found shall be remedied and a report 
made to Wire Chief. 

Electric Light, Power Service and Protection Panels and 
Distributing Panel Boxes 

A monthly inspection shall be made in each central office 
building of: 

1. Street and house panels, except when located in trans¬ 

former vaults. 

2. Distributing panel boxes. 

3. Electric light and power switchboards. 

4. Power protection panels. 

Panel boxes shall be inspected for: 

Improper type or unauthorized capacity of fuses. 

Improperly placed fuses. 

Loose connections. 

Reserve supply of fuses and fuse blocks. 

Electric lamp, where provided. 

General condition. 


126 


Fuses and Fuse Blocks 

A supply of each type of fuse shall be maintained in good 
condition at all times by either the Wire Chief or the engineer. 

Where removable fuse blocks are used, an extra block 
equipment with fuses shall be kept in each panel box. 

At buildings where there is a licensed engineer, he shall 
be responsible for replacement of fuses, maintenance of neces¬ 
sary stock, routine inspections and cleaning of equipment. At 
other buildings, the Wire Chiefs force shall be responsible 
for this work. 

Where extensive cleaning is necessary, the work will be 
done by the janitor under direction of the Wire Chief or his 
representative. 

Switchboard Framework, Electric Light Conduits and Foot 
Rails 

Each month a test of switchboard and local desk frame¬ 
work, foot rails and electric conduits shall be made to deter¬ 
mine whether or not they are grounded, or crossed with 
electric light circuits. Troubles found shall be referred to 
the Wire Chief. Test shall be made by the use of a test re¬ 
ceiver at each section from the front of the switchboard to 
see that the foot rails are clear of grounds, and that conduits, 
switchboard and local desk framework are grounded. 

Conduit and Floor Plan 

All members of the Wire Chief's force responsible for the 
operation of machines shall familiarize themselves with the 
location of conduits. 




127 


Live Bus Bar for Message Register., RB.Ex.or other important C.O. Battery feeders. 



Fig. 27. Fuse Alarm Signal—#24 Type Fuses. 

(See page 120) 


128 























































Battery Bus Bar 


To ruse Alarm 



Fig. 28. Fuse Alarm Signal for Central Office Fire Drill 

Bell—#24 Type Fuses. 

(See page 120) 


129 











































































Live Bus Bar for Message Register., RB.Ex.er other important C.O.Baiiery feeders. 



c 

a> 

O 

O' 


oc 

o 



Fig. 29. 


Fuse Alarm Signal—#35 Type Fuses. 

(See page 121) 


130 

































ToMessage Register 


1 1 ,Amp Fuse 

- Co o> 


Fig. 30. Message Register High and Low Voltage Alarm. 

(See page 122) 


131 






















































Fig. 31. Ringing Generator. Low Voltage Alarm. 

(See page 122) 


132 





















































VENTILATING PLANTS 


DEFINITIONS 

Air Pump 

A device used for compressing air for the operation of 
the automatic valves. 

Automatic Valves 

Valves operated by compressed air and controlled by 
thermostats and humidostats. 

Diaphragm 

That portion of the automatic valve operated by compressed 
air. 

Duct —See Ventilating Duct 

Fan 

A mechanical means for circulating air through the venti¬ 
lating ducts. 

Heating Coils 

Steam pipes mounted in the intake ducts. 

Humidifier 

A device for introducing moisture into the air. 

Humidostat 

A device operated by the amount of moisture in the air. 
Register 

An adjustable opening in the duct. 


133 


Screen 


A cheese-cloth covered frame used to filter the air. 
Thermostat 

A device operated by changes in temperature. 

Ventilating Duct 

A sheet metal casing used to convey air. 


DESCRIPTION 

Ventilating plants are installed in central office buildings 
for the purpose of supplying fresh air, and removing the 
foul air, thereby avoiding, to a great extent, the necessity 
for opening windows. 

Fresh air is drawn from suitable points outside the building 
and after being screened is forced, by means of large fans 
operated by an electric motor, through ducts, which terminate 
in registers near the ceiling of the operating rooms, the foul 
air being expelled through similar ducts which terminate 
in registers at or near the floor. 

During the winter months, it is not desirable to deliver 
the air into the operating rooms at the outside temperature, 
and it is therefore suitably heated before it enters the ducts. 
This is accomplished by the use of heating coils placed near 
the mouth of intake and is automatically controlled by means 
of thermostats after the steam has been turned on at the 
required number of heating coils. 

During the winter months the air should be 70° F. when 
delivered to the operating rooms. 

Regulation of Temperature 

A thermostat located in the intake duct is so arranged that 
it opens and closes a by-pass, thereby regulating the supply 
of cold air when the room temperature varies 2°F. above or 


134 


below normal. Another thermostat, located at the mouth of 
the intake, controls additional steam coils and is set to operate 
in extreme cold weather. Thermostats are also located in 
the operating and other rooms in connection with steam 
radiators and should, in general, be adjusted to open the 
valves at 68° F. and to close them at 70° F., but may be 
regulated according to the variation in temperature in dif¬ 
ferent portions of the room. 

A pump is used to compress the air for operating the auto¬ 
matic valves in the ventilating room and at steam radiators 
in operating and other rooms. When the pump is in opera¬ 
tion, the diaphragm in the valve remains operated until the 
temperature of the room falls below the required degree of 
heat. The operation of the thermostat releases the air pres¬ 
sure and a spring forces the diaphragm in the opposite 
direction, thus opening the valve and permitting steam to 
enter the heating coils. When the temperature rises to 
normal the thermostat operates and the compressed air forces 
the diaphragm back and cuts off the steam from the heating 
coils. 

Regulation of Humidity 

A humidostat for regulating the humidity in the air is 
located in the intake duct in the ventilating room. This 
humidostat controls a valve which automatically opens and 
closes as the humidity varies from a pre-determined point 
and should be regulated according to weather conditions, or 
so that the humidity of the air in the operating room will 
be maintained at approximately 70%. 

OPERATION 

Whenever the ventilating plant is started or stopped the 
following operations are necessary in the order indicated: 

To Start 

1. Open shutters in intake. 

2. Start motor. 

3. Turn steam on heating coils. 

4. Turn steam on humidifier. 


135 


To Stop 

1. Stop motor. 

2. Close shutters in intake. 

3. Turn steam off humidifier. 

4. Turn steam off heating coils. 

NOTE: Operations 3 and 4 are unnecessary except when 
steam plant is in service. 

In case of fire in the immediate vicinity of the central 
office the ventilating plant motor shall be stopped and intake 
shutters closed at once. This will prevent smoke being car¬ 
ried into the operating room through the ventilating system. 

In certain cases, such as on very hot nights when it is 
not desirable to stop the ventilating plant as scheduled, 
arrangements may be made to have the Real Estate Depart¬ 
ment watchman do the necessary work. 


CARE AND MAINTENANCE 

Cleaning Motor 

The motor and starting box shall be cleaned daily and 
weekly as described in the section on “Motors and Gener¬ 
ators”. 

This work shall be done as near 8:00 A.M. as possible and 
two additional inspections of the motor shall be made during 
the day. 

Maintenance 

The Wire Chief will maintain the ventilating motor with 
associated apparatus and that portion of the waring which is 
located in the room occupied by the motor, and wfill make 
minor adjustments to thermostats, humidostats and associated 
apparatus. He will also be responsible for the proper opera¬ 
tion of the ventilating system. The Real Estate Department 
will maintain ducts, fans, screens, registers, heating coils, 
humidifiers, thermostats, humidostats, automatic valves, air 
pumps and associated apparatus. 


136 


ROUTINE TESTS, INSPECTIONS AND 

REPORTS 


MOTORS, GENERATORS AND ASSOCIATED 

APPARATUS 

Page 

Hourly: 

Inspect commutators of direct current motors and 

generators in operation. 19 

Inspect bearings of machines in operation. 23 

Daily: 

Inspect oil rings of machines in operation. 23 

Weekly: 

Test reserve sets by operation. 13 

Inspect and clean contacts of circuit breakers. 24 

Test circuit breakers. 25 

Test starting boxes. 25 

Inspect starting boxes and rheostats for general 
condition . 25 

Monthly: 

Inspect and clean hollow shafts of ringing machine 
interrupters . 23 

Annually: 

Inspect all power board connections. 24 


137 












MERCURY ARC RECTIFIER SETS 


Page 

Annually: 

Inspect all connections of rectifier and associated 

apparatus . 50 

Inspect oil in transformer. 50 

EMERGENCY CHARGING SETS 

Bi-Monthly: 

Inspect complete set. 73 

Test under full load. 73 

STORAGE BATTERIES 

Daily: 

Report of charge, etc. 86 

Weekly: 

Report of overcharge. 87 

Inspection for heating or corrosion at connections.. 91 

Semi-Annually: 

Report of discharge.86 and 87 

Annually: 

Inspection and adjustment of electrolyte. 88 

Special: 

Report of Two-Plate Cells. 89 

Report of irregularities in connection with battery 

or charging circuit. 89 

Emergency troubles . 90 


138 













PRIMARY BATTERIES 


Page 

Daily: 

Test of coin collector battery. 99 

Test of voltmeter testing battery. 100 

Weekly: 

Test of coin collector battery. 99 

Test of main ringing battery. 99 

Test of superimposed ringing battery. 100 

Test of superimposed bell adjusting battery. 100 

Test of booster battery. 101 

Test of operators’ transmitter battery. 101 

Test of P.B.X. emergency battery. 101 

Test of miscellaneous dry batteries. 101 

Special: 

Inspection of caustic soda batteries. 99 

POLE CHANGERS 

Weekly: 

Complete inspection and test. Ill 

MISCELLANEOUS POWER AND LIGHTING 

APPARATUS 

Daily: 

Inspect tools for replacing fuses. 116 

Inspect fans when in operation. 123 


139 
















Page 


Weekly: 

Inspection of power fuses. 116 

Test and inspection of extension cord outlets. 126 

Test and inspection of drop, portable and emergency 
lamp cords . 126 

Monthly: 

Inspection of mica fuses. 118 

Test of ringing generator alarm. 122 

Test and inspection of fans. 123 

Inspection of electric light, power service and protec¬ 
tion panels, and distributing panel boxes. 126 

Test of switchboard framework, electric light con¬ 
duits and foot rails. 127 

Quarterly: 

Inspection of resistance lamps. 119 

Annually: 

Test and inspection of fuse alarm drops. 121 

VENTILATING PLANTS 

Daily: 

Inspect motor for proper operation. 136 


140 





























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